Using classic Outlook for Windows in business environments
I just resolved this problem utilizing the Microsoft Help service. In my case, the problem was that my Resolution setting was too high, so the bottom of the Notification or Pop-Up did not appear and I was unable to scroll or move the the Pop-Up to bring the critical "Learn More" (or words to that effect) Button into view on my 14" laptop. By reducing my type size way down, the full Pop-Up appeared on the screen, revealing the critical button which allowed me to jump thru the requisite Microsoft hoops and resolve the Pop-Up.
To address the Resolution issue, in Windows 11 just click on your START button, then select Settings, Display, Scale (in the section entitled "Scale & Layout"). My size setting had been 175%. I reduced to 100%, which did the trick. But you may want to go lower until the full Pop-Up is in view on your screen.
None of this should have been necessary, of course. Oh well...