If ameliuspay is properly registered with the EU payment processor platform, then it should automatically appear as an option in the webshop.

What does that even mean, and how is that "EU payment processor platform" not a payment processor itself, meaning that you're mandating one specific payment processor?

Hacker News moment. Imagine someone over 60 whose career has nothing to do with computers trying to make sense of a list of 45 different payment processors to choose from.