Tried "everything" and still can't play!

@sinceage12  If OneDrive is running on this computer, try pausing syncing before you play.  Right-click the cloud icon in the lower-right corner of the screen to see the option.

If that doesn't help, create a new admin Windows account and try playing there.  Make it local, as in, don't link it to your Microsoft account.  You'll be able to (try to) launch Sims 4 without reinstalling anything.

If that doesn't help either, please do a clean uninstall and reinstall of both the game and the EA App.  Start with Sims 4:

• Put aside your Sims 4 folder in Documents\Electronic Arts, if you have one, and rename it to something that doesn't include the words "Sims 4."
• Download Revo Uninstaller (the free version is fine) from here.
• Launch Revo, select Sims 4 from the list, and click Uninstall.
• Once the game is uninstalled, select "Moderate" under "scanning modes," and click Scan.
• Review the list, in case there's something you want to save; otherwise, click Select All, and then Delete.
• Close Revo, and restart your computer.

Uninstall the EA App with Revo as well.  I don't have instructions for that at the moment, but the process should be straightforward.  Restart again when you're done.

Install the EA App, then create a new folder into which you'll install Sims 4.  The folder should be on the root level of the drive of your choice, for example C:\Games is fine, but not C:\Program Files\Games.