The forementioned mods folder under documents is only where you'd place mods downloaded from Nexus etc, to use in modded gameplay. I am under the impression you only mean to play the game with mods, rather than make mods yourself, right?
If so, you'd just need to place downloaded mods' .pak files under \Users\Me\Documents\Larian Studios\Divinity Original Sin 2 Definitive Edition\\Mods\. If there isn't a \Mods\ folder there, just create one, then start throwing those juicy .pak files in there from the mods you've downloaded
