Acrobate Pro X does not send forms (organize with acrobat.com option)

Hello,

I want to send forms and use the first option, where responses are automatically downloaded and I can organize the forms with Acrobat.com.

When I send the forms, I receive an error message: "Acrobat could not create your workspace on the server. Try again."

Then: "There could no folder be opened in the declared unlocked folder or hosted service."

And: "Sending forms was aborted."

Why is that? Do I have to link my Adobe-ID to the product Acrobate Pro X by its serial number? And if so, is there any option to do this with volumeseries?

(I only have the German version installed, so I only receive German error messages but tried to translate them here. They might differ to the original ones.)

Thank you for your help!