To create a custom integration with a cash payment gateway, you perform the following steps:
Create the gateway extension. See Cash payment extension details for information specific to this extension.
Upload the extension to the administration interface.
Enable the gateway for the sites that require it.
Configure the Generic Payment webhook by specifying the gateway URL and the username and password. (See Process the order.) Note that webhook settings are not site-specific. The configuration you supply applies to all sites that use this webhook.
