Hello Münchow

Thank you for your purchase.

Please note that the only supported language is English, so please translate your further messages.

In Amelia settings you can only connect to your existing PayPal app, and if the credentials are good, it should work. Please note that if you're using Test credentials, you won't be able to test the payment with a live account, and vice-versa - you can't run a test transactions if you enable Live credentials.

Please try this, and check out our instructions for Payment systems. If you're still not able to get it to work, 

Please provide me a temporary WP-admin login for your site where this happens, so we could log in and take a look ‘from the inside’ as that’s the most efficient way to see and resolve the issue. We do not interfere with any data or anything else except for the plugin (in case that’s a production version of the site), and of course we do not provide login data to third party. 

You can write credentials here just check Private Reply so nobody can see them except us.