spicylibra Please double-check that you don't have a second antivirus running. It's common to have one installed on a laptop, and sometimes there's one present on a prebuilt desktop too. The Error 21 is almost always antivirus-related.
If you can't find another AV, please create a new admin Windows account and try playing there—this will get around any other permissions issues related to your main account. Make it local, as in, don't link it to your Microsoft account or any email address. You'll be able to launch the game without reinstalling anything, but your saves and other user data won't be available. That's fine and can be fixed later if necessary.
Gwendy1998 Please see my previous post, and if that doesn't help, try the new admin Windows account as described above.
