Ter590 Are you still getting the Windows Security error? If so, that's the issue, or at least the immediate one, and you need to find a way to unblock it. If you don't see anything under Defender's regular settings, and nothing under Controlled Folder Access, do you have Smart App Control running?
And just to confirm, you did in fact remove or rename the Sims 4 folder in Documents > Electronic Arts? Your post mentions the clean folder/factory reset, but I want to make sure you did it AND that it worked, as in, the folder didn't copy instead of moving, and there's no content inside the new folder that's from your previous one.