Endless Sign-in loop

[SpikexArt]

When I open Adobe DC, I am prompted to sign in. I click sign in, (username, password, Adobe Authenticator app) and it tells me says that I am signed in. However, when I open Acrobat DC and click the file I want to use, it asks me to sign in again. And again. And again. And again....

I am using a MacBook Pro with OS X version 10.13.6, and version 2021.001.20155 of Adobe DC installed. The computer is old and cannot be upgraded further. Everything was working fine until about 4 or 5 days ago.

I also followed the instructions here: https://helpx.adobe.com/in/download-install/kb/adobe-sign-in-loop.html to no avail.

Thanks!

[Lilybiri]

Sorry, but this seems to be posted to the wrong forum. This is the Captivate forum, I'm not sure which application you are pointing at: Acrobat or ???