This isn't like the Sims 3, where you need to make the Mods folder. In the Sims 4, it's the game that generates the Mods folder automatically with a resource.cfg file inside. If you didn't let it do it, resource.cfg must be missing and that's why mods don't load.
Move mods to a safe place, delete your Mods folder, start the game and it will generate a Mods folder with resource.cfg inside. Quit, check it's all there and only then move your mods to this folder. Restart the Sims 4.