Tested with OpenCart versions:
220.127.116.11 - 18.104.22.168
Upload the plugin in your OpenCart system using the OpenCart installer tool.
In the OpenCart administration interface, go to Extensions and select Payments. In the list of payment methods that appears, click on the Install icon next to the OPAY plugin. Once the plugin is installed, click on theEdit icon.
Fill in the mandatory settings for the OPAY plugin and click on the Save icon. If your online store is not registered with the OPAY system, fill out the registration form and receive all the necessary data for the settings.