I'm on Mac Catalina 10.15.5 and about 19 hours ago I received a popup from Creative Cloud while using Photoshop telling me to confirm my phone number in case I wanted to enable two-factor authentication. I did so, and ever since I have been stuck in a sign-in loop on both Photoshop and Creative Cloud. Before this, I'd only had photoshop for roughly three days and it worked fine for those three days. Each time I open either programme now though, I get prompted to sign in (my email address is already filled in and I cannot change it) and the only thing I get to do is push the sign-in button or close the popup, which closes Photoshop as well (or in the case of Creative Cloud it's just creative cloud that closes). If I press the sign-in button in Creative Cloud, I get a loading screen for a very long time and then I get told that I was logged out and need to sign in again. If I press the sign-in button in Photoshop, the popup closes for a second and reopens immediately.
Yesterday, after following multiple online solutions and completely reinstalling both applications I contacted Adobe support and over the course of four hours and three tech support people, a solution could not be found. Things that either the tech support people who helped me or I have done so far:
I've tried just about anything tech support, the internet, and I could think of but I'm just stuck now. After all these steps there has been no improvement whatsoever. Does anyone know how to fix this?
So after I posted this thread, I started fiddling with it again to try and fix it. One thing that occurred to me while reinstalling the applications again was that when it started, I was prompted to verify an email address and enable two-factor authentication, but during the fixing process, that kind of suddenly stopped out of nowhere, or it at least did it very selectively since I only have 7 of those text messages from adobe whereas I had to log in way more often than that. So, I looked at my account's security settings, and lo and behold, two-factor authentication was suddenly turned off. When I turned it on again and started photoshop again, I could log in with my email address and got a text message, filled in the code, and it's fixed! I don't know how long it will last but for now, it is fixed.
If anyone reading this has the same trigger for this issue with Creative Cloud prompting you to verify a second email address and use your phone number for two-factor authentication, please check in your adobe account's security settings if you have two-factor authentication turned off, you might need to turn it back on to fix it. From my four-hour-long experience with tech support, I can tell this is not really their first solution, but it worked for me and it is honestly the easiest solution out there out of the ones that I've tried.