I have now checked everything again and I have noticed a few more problems.
As in a previous ticket (#158707), immediate payment was not configured - I have now changed this with “https://flybikes24.de”.
However, we still only get to the payment notice and back to the store - but the payment is not triggered.
Do you have any documentation on what we need to activate and set up with PayPal - independent of your documentation regarding EasyStore?
I am currently assuming a problem on the part of PayPal administration, so that we are not receiving correct data.