Ich kann mit AC pro nicht arbeiten, obwohl angeblich ein Abonnement besteht.

@andreas_0587 it looks correct. It says you bought Acrobat pro and AI Assistant too! 

By any chance did you EVER have a previous installation of Acrobat Reader or an expired trial version of Acrobat Pro can absolutely cause conflicts and licensing issues. This is a very common scenario and is often the root cause of the problem you are experiencing. If so, I would uninstalling the application through adobe.com or Creative Cloud Desktop App, but also using a special Adobe tool (the Adobe Creative Cloud Cleaner Tool) to remove all remnants of previous installations, including old license files and settings, before you download a 'fresh' installer, and install the new, paid version from Adobe.com or Creative Cloud Desktop App.