Normally the game gets installed to C:\Program Files (x86)\Origin Games\The Sims 4.
You're most likely looking in the wrong folder for your user files. The Sims 4 folder is normally located in:
C:\Users\Username\Documents\Electronic Arts\The Sims 4
After a game has been started.
Did you start the game so it can create a Sims 4 folder in your Documents folder?
Though it can be manually moved. If it is not there, you may need to search for it to find out where it was moved to.
In the Sims 4 folder is where you can find folders such as Mods, Saves and Tray folders. Once you find out where your Sims 4 folder is located you can then move your files into their appropriate folders.
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Reference Link:
My Sims User Folder or Install Files are Missing?
https://www.carls-sims-4-guide.com/forum/index.php?topic=29315.msg431335#msg431335