Import - All the assets textures, models to import custom assets in the Asset Editor are placed here. ColorCorrections - Custom color corrections look-up tables can be placed in this folder. Assets - Assets saved from the Asset Editor are stored here. This directory contains all the DLLs for moddingoutput log and more. The other directory you might need is located in your steamapps.
This is where you create all your modifications to the game. The main directory you will need for modding is located in local app appdata.