E_AUTH_BAD_DEVICE_KEY_OR_PKCS12 (deleting KEY doesn't fix the issue)

Hi there!

two days ago, I bought an ebook for the first time and so I downloaded Adobe Digital Edition (ADE). Unfortunately, when I try to open the .acsm-file in ADE I receive the following message:
E_AUTH_BAD_DEVICE_KEY_OR_PKCS12

What I've already tried:
I deleted KEY under HKEY_CURRENT_USER\Software\Adobe\Adept\Device.
Afterwards, I tried to erase my authorization:
ADE --> Help --> Erase Authorization --> password, confirm, confirm eingegeben
I then get the following message: "Unable to Erase Authorization. Please try after some time."

I waited 24 h hours between two attempt of erasing my auorization and I still ge this message, so I don't thing time is an issue here.

I already downloaded the .acsm-file several times but no change.

Unfortunetaly, I don't have another ebook to test whether I have this problem with different .acms-files.

System: Windows 10
ADE-Version: 4.5.10. ...

I hope you can help me!

Best wishes,

KD