Hey @yetanotherglitch,
Sorry to read that you encounter the "Certificate Authentication Failed" error.
The best way to fix that is to upgrade your OS.
If you don't want to do that, you will need to follow the following developer's troubleshooting steps: "Certificate Authentication Failed" error troubleshooting
Please note this troubleshooting will only fix your game until October. Then you will need to update to Windows 7 or newer.
Good luck and I hope that you will be able to get back to the game soon.
