To install the new module, upload it to the /modules/gateways/ folder of your WHMCS installation.
If the module includes a callback file, that should be uploaded to the /modules/gateways/callback/ folder.
Once uploaded, navigate to Setup > Payment Gateways to activate and configure the new module.
Important Note The process of activating a module detects the type of module that has been created. Therefore if you experience unexpected behaviours, please try deactivating and reactivating your module before continuing.
If you receive a blank page or error message within the Setup > Payment Gateways page upon uploading your new payment gateway module, this indicates there could be a syntax error within the new code.
To debug this, you can turn on error reporting. To do this, navigate to Setup > General Settings > Other and check the Display Errors setting.
This enables PHP error reporting and should show the cause of any issues. Once resolved, remember to disable Display Errors again.