The structure of Resource.cfg file allow you to create up to 5 levels of subdirectories into the Mods folder. Btw, if you have problems and the game doesn't load your custom contents, try to move it together with Mods folder to Programs/Electronic Arts/The Sims 3 World Adventure. You don't need to move this file into Programs/Electronic Arts/The Sims 3 World Adventure folder, the game read it even if placed into Programs/Electronic Arts/The Sims 3. This file is compatible with World Adventure. In my old TS2 folder I have, in addition to the Downloads folder (not inside), the following: Walls and Floors, Objects and Recolors, Hacks and Mods, and 4 other folders with my own walls and floors, painting replacements, skin defaults, and face template replacements. The Sims 3.app > Contents > Resources > transgaming > c_drive > Program Files > Electronic Arts > The Sims 3. At some point you could place some CC folders outside the Downloads folder. The path to find the right folder should be something like this Resource.cfg file is the same and both the folder where insert it is the same. Keep Resource.cfg from your desktop and insert it on Programs/Electronic Arts/The Sims 3.

Usually it should be on Programs/Electronic Arts/The Sims 3 of the hard drive where you've installed the game (default is C:). WHERE IS INSTALLED not in the saves folder on Documents. Go to the drive and folder where you've installed the game.

Sims 2 mods folder