Abo Code wird nicht akzeptiert

the is almost certainly for a first year subscription and that's why you can't use it.  ie, read the fine print and the user comments on amazon.

if you still want to contact adobe to confirm, you can use phone or twitter.

using a browser that allows popups and cookies, contact adobe support by clicking here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
in the chat field (lower right), type AGENT
be patient, it can take quite a while to reach a human

p.s. if you're contacted by anyone (via email or private message), it's much more likely to be a scammer than an adobe representative. ie, double check for an employee badge if contacted in the forums and look for an adobe.com domain in the email address if you click reply to an email. then check again and be very suspicious. any other method of contacting (or offering to contact you) is almost certainly a scam, https://community.adobe.com/t5/using-the-community-discussions/staying-safe-in-the-adobe-support-community/td-p/12919684/redirect_from_archived_page/true.

p.p.s you can also use phone (but chat is usually quicker), https://helpx.adobe.com/contact/phone.html

p.p.p.s. you can also use twitter to tweet @AdobeCare.