Visit your OXID backend and navigate to Extensions > Modules > Ratepay > Root to deactivate your current Ratepay Payment Plugin.
Remove the folder pi which you can find in
{shop-root}/source/modules/.Connect via ssh to the server where to find your shop installation and it's vendor folder.
Install the Ratepay Payment Plugin by executing the following command:
composer require ratepay/oxid6-paymentVisit your OXID Shop backend and navigate to Extensions > Modules and confirm with Yes that the old configuration can be deleted.

Visit your OXID Shop backend and navigate to Extensions > Modules > Ratepay > Root and activate your all new plugin.
Visit your OXID Shop backend and navigate to Shop Settings > Payment Methods to activate your Ratepay payment methods.
Go to Ratepay Setting