If you run a WooCommerce store in Guyana, adding MMG at checkout can improve trust and reduce checkout drop off. The key thing to understand is that MMG checkout is not only “install a plugin”. You must first become an MMG Merchant, submit documents, generate keys, request credentials, complete sandbox tests, then get production approval.
This guide walks you through the full process in the correct order, then shows you how to configure the Revamped GY MMG Checkout plugin (including the Importer, Verify Payment, Resend Payment Link, Logs, Diagnostics, and Exports).
Quick summary
To use MMG on WooCommerce checkout, you must: (1) become an MMG Merchant, (2) generate RSA keys, (3) install the plugin and copy the callback URL, (4) request sandbox credentials and whitelisting, (5) pass sandbox testing and MMG verification, then (6) switch to production credentials and run a live test payment.
What you need before you start
A WordPress website with WooCommerce installed
WordPress admin access
Access to your hosting panel or cPanel/Plesk
A computer with OpenSSL (Windows, Mac, or Linux)
Time and patience, because there are multiple approvals and checks
Step 1: Become an MMG Merchant
To receive payments and settle funds to your bank account, you need an MMG Merchant account. Start the merchant signup using MMG’s form or email. Email is often faster. Also ask for a WhatsApp contact for merchant support to speed up follow ups.
Step 2: Prepare your merchant documents
MMG will send a checklist. Common minimum items usually include: ID, proof of address, business registration, business proof of address, banking letter or statement, and a TIN certificate. MMG may also send forms like a Partner Form, Anti Corruption Questionnaire, and a Merchant Agreement. Complete them carefully and return them.
Step 3: Generate your RSA keys (public and private)
MMG integrations commonly require RSA keys. You generate a private key first, then derive the public key from it. The public key is shared with MMG. The private key must remain private.
If you are using Windows, you can do this with OpenSSL in Command Prompt by generating a 2048-bit RSA private key then generating the public key from it. Keep the private key secure and do not send it to anyone.
Step 4: Install the MMG WooCommerce plugin
Install and activate the Revamped GY MMG Checkout plugin on your WordPress site. This plugin supports both WooCommerce classic checkout and WooCommerce Blocks checkout.
After activation, go to:
WP Admin → MMG Checkout → Settings
From there, copy the Callback URL shown in the settings. You will need this callback URL when requesting MMG credentials.
Step 5: Request your API credentials from MMG
Email MMG Merchant Services and request the credentials needed for WooCommerce integration. Typically this includes: Merchant Client ID, Secret Key, sandbox details for testing, and any required setup information.
In your email, include:
Merchant account name
Phone number registered to the MMG account
Merchant ID
Callback URL (success and error), copied from the plugin settings
Your RSA public key (paste it or attach the file)
MMG will usually issue sandbox credentials first so you can test before they approve production.
Step 6: Provide your production IP for whitelisting
MMG may ask for your store’s production IP so they can whitelist it. The cleanest method is to check your hosting dashboard or ask your host support. If you use Cloudflare or another proxy, confirm the origin IP with your host, because a ping can show a proxy IP instead.
Step 7: Configure the plugin and run sandbox tests
When MMG provides sandbox details, configure the plugin and run complete end to end tests.
Fastest setup method (recommended):
WP Admin → MMG Checkout → Importer
Upload the zip MMG provides and the plugin will locate the standard files and auto configure settings. If a zip is not available, upload the files separately (setup.cfg, public key, private key).
During sandbox testing confirm the full flow:
Customer selects MMG
Redirect to MMG works
Return to the store works
Order status updates correctly in WooCommerce
Transaction details save on the order for order history and invoices
Step 8: Submit evidence and complete MMG verification
After sandbox works, update MMG. They may ask for a live demo call, screen recordings, or specific test scenarios. This is normal. It is part of their approval process before production.
Step 9: Go live with production credentials
After you pass testing, MMG issues production credentials. Import the production zip or files in the plugin, switch to Live mode, then run a small real payment end to end to confirm settlement and order status updates.
Go live checklist (do this before taking real payments)
Switch Mode to Live
MMG Checkout → Settings → Mode: LiveImport Live credentials
MMG Checkout → Importer → Import Production zip or filesConfirm callback URL in MMG portal
Set both success and error URLs to the callback URL shown in the plugin settingsRun a small real payment test
Run a small transaction end to endConfirm everything updates properly
Order status updates correctly
Customer receives the paid order email
MMG transaction details appear on the order
Customer can see the paid order in My Account → Orders
Your invoice plugin reflects the paid status
Common issues and quick fixes (FAQ)
“Order stuck on Pending payment”
Most common causes are wrong callback URL, wrong mode, or keys for the wrong environment. Confirm mode, re-import the correct files, confirm the callback URL matches the plugin settings, then run Verify payment if MMG shows paid.
“Customer paid but closed the tab”
Use “Verify payment” in the order. If it is not paid, use “Resend payment link” to send a fresh link to the customer.
“MMG shows paid but WooCommerce not updated”
Use Verify payment first. If it still does not update, check Logs and Diagnostics. Most of the time it is callback misconfiguration, SSL issues, or a key mismatch between Live and Sandbox.
“I changed modes and now decryption fails”
This is almost always a key mismatch. Re-import the correct environment files and ensure Mode matches the imported files.
Security rules (be strict)
Do not email private keys or credential files around
Use the Importer to load credentials correctly
For production sites, prefer wp-config constants if you want secrets outside the WP database
Limit admin users and enable 2FA where possible
Keep WordPress, WooCommerce, and plugins updated
Use SSL, backups, and basic security monitoring
Need help? Revamped GY can do the full setup.
Merchant onboarding, document checks, key generation, plugin setup, sandbox testing, verification, and going live can be tedious. If you want it done correctly without stress, Revamped GY can handle the full process from merchant onboarding guidance to a working checkout.