Windows 10 user here and original discs owner.
I followed your steps and while it did get the game in my EA App, it gave me an error that states: "The Sims Medieval cannot run. The installation is incomplete. Please reinstall and try again."
So the troubleshooting began. I reinstalled the game 3x, repaired 3x, uninstalled and reinstalled the EA app all with no luck. I contacted EA support and they had no additional advice other than sending me these two links:
https://help.ea.com/en/help/ea/ea-app/game-download-install-load-troubleshoot/
So, I tried the first link since the game did appear in the EA app and I happened to notice there was no product key in the properties area like my other Sims games, even though it was entered on thesims3.com.
In order for the game to recognize my valid key, I had to install both the base game and the EP discs. My product key then appeared in the EA app.
I then had to uninstall the EP, reboot, uninstall the base game and reboot. I then re-installed the game via the EA app.
In order for the game to launch for the first time I had to change the compatibility mode to Windows 7. The game then informed me it didn't recognize my graphics card. So I closed the game, and ran Graphics Rule Maker to have the game recognize my card. Then I removed the compatibility mode.
After completing all these steps, I am now able to run the game with no issues. I'm assuming if I get a new PC or upgrade from Windows 10 to 11 all I'll have to do is run the Graphics Rule Maker and install via the EA app.
Just posting this in case it could help someone else out, or if I need it again in the future.
