Mod folder have static location: C:\Users\%USERNAME%\Documents\Electronic Arts\The Sims 4\Mods
Standard mod content includes some .package files and, occasionally, some loose scripts with (but in most cases without) sub-folders usage.
I. e. if mod author didn't put the file into sub-folder it shouldn't be put into sub-folder in mods folder. Also, PLEASE no dedicated sub-folders for CurseForge mods. It breaks some script mods.