Consistent "One or More Files Requiring Update in Use" Update Error

@iButterfree  What antivirus program do you use?  It may be preventing Origin from properly installing Sims 4, either because Origin.exe is blocked or because TS4_x64.exe gets flagged.  The initial error you saw is often related to the game .exe being blocked or even deleted.

You can try setting exceptions for both .exe files in your antivirus, but that's often not enough—some programs have additional features that need to be disabled.  If you just want to cut through the various options, you can disable your antivirus entirely while downloading, then mess with its settings after the fact.