@lollyfarberabe The Sims 3 folder in Program Files contains the game's program files, as in, what Origin or the EA App installs. The folder in Documents > Electronic Arts is the user folder. If you move the game's program files, then of course the EA App is going to think Sims 3 is no longer installed and prompt you to download it again. That's why the suggestion is specifically to move the folder in Documents.
The error you saw when trying to move the folder in Documents may be due to OneDrive, so please let me know whether it's running, even if you don't use it, and how full it is.
Thank you for the clarification. I know it may sound obvious to most people but as I said, I'm really not knowledgeable in this kind of matters...
So, I did as instructed and it seems to work. I'll see tomorrow if my store content stays installed or not after restarting my computer. If it does, many thanks to you for figuring out this solution, I've been struggling with this for nearly a week.
