First of all, you need to download the source code of the FreedomPay plugin for OpenCart. This can be done by requesting it from the FreedomPay manager, or (a simpler and faster option) - download it from the OpenCart marketplace page.
To install the FreedomPay payment gateway plugin, you need to follow a few simple steps:
Go to your site's Dashboard:
Select the “Extensions” item on the left side, in the menu that opens, select “Installer”.
Click "Upload" blue button in the top right corner and select the file with the plugin.
If the uploading is successful, the FreedomPay payment extension will appear in the installed extensions list. Next you need to click on the "Install" green button in the same row, as the FreedomPay plugin is.