PSE 2021 continuously asks for registration after installlation

Hello,

I just installed PSE 2021. When starting the software (Editor) for the first time, I'm asked to register. After entering ID and Password, the software should then ask for the serial number. Instead, it freezes for a few seconds and then returns back to the first window, asking again for registration.

I checked my account on the adobe website and it works with my ID and password. I also switched of my virus protection and firewall in order to make sure it doesn't block the process.

Nothing works, I'm still stucked in the first step for registration.

Thanks for any help