Not sure why this is happening. I deleted the old installation from both Unity Hub and Finder on my Mac. I actually had installation issues with 2021.3.2f1 before it got installed successfully so I deleted and reinstalled both Unity and Unity Hub.
If I click ignore and open the project, I get a pretty long "DirectoryNotFoundException: Could not find a part of the path" error -- and apparently I can't add scripts to any object because of this error: "DirectoryNotFoundException: Could not find a part of the path '/Applications/2021.3.2f1/Unity.app/Contents/UnityReferenceAssemblies/unity-4.8-api/Facades'."
Plus, I noticed that in this project's folder, the "Assembly-CSharp.csproj" file is not there. I see the file in all my other projects which were done in the previous editor version (2020.3.30f1).
What does the safe mode and directory error mean though? Did I do anything that caused this? What should I do? I'm on Mac btw. Any help is appreciated, thanks.