If you are trying to pay for a membership using a german Paypal account, there's a chance you're getting an error message on the Paypal page. This can be sometimes caused because Paypal has some legal limitations for recurring payments done with german Paypal accounts.
We've found this problem to be sometimes caused because there isn't a credit card linked to the Paypal account. If that's your case, you can try to link your credit card to your Paypal account and try the payment again.
If you keep getting this error, we're sorry to say that due to this Paypal limitations we're not able to provide paid services to customers in with german Paypal accounts.