In the Origin app, right-click on the gear icon next to the Play button and select "Repair".
@Uniquarn14 I've merged your post with the master thread for this issue. Please try repairing the game in Origin: open your game library, right-click on the Sims 4 icon, and select Repair.
For the Medieval issue, if your computer runs Catalina or Big Sur, that's the issue: Medieval is a 32-bit app, and the OSs are 64-bit only. There's no way around this, except to play in a different OS or on a different computer. You could in theory partition your hard drive and install Windows on one side, but it sounds like you don't have nearly enough drive space for that. Or, if you have at least temporary access to a Mac running Mojave or earlier, you could install Mojave on an external hard drive and boot into that to play.
https://bluebellflora.com/running-32-bit-apps-after-macos-mojave/
If you only recently bought Medieval and don't want to bother with the workarounds, you can request a refund from EA:
https://help.ea.com/en-us/help/account/returns-and-cancellations/
