This might happen if you downloaded one of the unofficial AMBOSS Anki add-ons from the Anki website. If this is the case, please remove the add-on through the Tools > Add-ons menu in Anki.
Once you complete the removal process, you can download and install our official add-on here.
If the problem persists, please make sure you're logging into Anki via the account you have active access with, or try resetting your AMBOSS account password at this link. If you need further assistance, please feel free to contact the AMBOSS Support or leave us a message here and we'll get back to you as soon as possible.