Can't log in to Adobe Acrobat Pro 2020 Student & Teacher

[Tim_____________]

I have bought "Adobe Acrobat Pro 2020 Student & Teacher" and have already received my serial number. When I start the programme, it first asks for the serial number and then asks me to log in with my Adobe account. Every time I try to log in, I get the error message "Unfortunately, an error has occurred. Please start Acrobat first or contact your administrator. {h0}More information{h0} "
I have already deleted and reinstalled everything several times and tried other versions. Whenever I log in, I get this error message. The service from Adobe is poor, no contact form and also no support via a chat (although it is claimed in various places that there is a chat).

[MeenakshiNegi]

Hi Tim_____________,

Thank you for reaching out.

As mentioned above, you cannot sign in to the application. If you are still experiencing the issue, try removing the application on the machine and rebooting the device. 

Then reinstall the application from the following page: https://helpx.adobe.com/download-install/kb/acrobat-2020-downloads.html.

Use the steps as suggested in the help document to install the application.

If the issue still occurs, let us know.

Thanks,

Meenakshi