I logged in several devices and I know there's a limit of 2.
The problem is that each time I access Acrobat Reader I have to wait several time for the attached panel to open and do another login.
Is there a way to manage your devices? the page here is empty: https://account.adobe.com/activated-devices
Are you using Adobe Reader with same account on two different devices simultaneaously?
Would you mind sharing the version of the Acrobat Reader DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version 21.07.20095 (Win) , 21.07.20096 (Mac) installed. Go to Help > Check for updates.
Also try to logout of the application, reboot the computer once and relogin with the same Adobe ID and see if that works for you.
Let us know how it works at your end. If you have any further queries please feel free to reach out to us.
I have v21.07.20099 installed, so i'm upodated.
I just made an installation repair (Help > Repair Installation) and it seems to work both in my first PC and in my phone.