You could try going into your profile and change your location to Germany or you may have to open a new account showing where you actually are located, which as you say, is Germany.
While yes, you can open an account on the USA.com site, you still have to show where you actually are. You are now running into issues with setup being asked questions that would only apply to the sellers that are located in the USA, same would be for shipping and payouts linked to this account. Managed Pay would be asking for a USA checking account.
