The mods folder is installed by default, along with it's Resource.cfg. As shown in the photos below.
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If you don't have this type of setup. You may want to try a Sims 4 factory reset, so the folder can be set up correctly.
Sims 4 Factory Reset - (What & Howto)
http://www.carls-sims-4-guide.com/forum/index.php?topic=29292.msg401669#msg401669If you want the Cheats Fix mod, download it and then copy it from where you downloaded it to your Sims 4 mods folder.
C:\Users\Username\Documents\Electronic Arts\The Sims 4\Mods
Make sure both mods/cc options are check marked in the Game Options.
-- Options > Game options > Other - Enable Custom Content and Mods, and Script Mods Allowed
You will need to exit the game and reload it for the mod to show as active when loading the game.
This mod does fix Skill Cheats -