Here's some info about mods: https://docs.google.com/document/d/15vAJ-VFSL1jmOnoM4_M9C63RM-08kKtKyzo6-t3amV0/edit and this thread https://itch.io/t/480093/mod-support-editor-link-and-documentation
Basically, you need to put mods into this folder: *game_folder*/IM_Data/StreamingAssets/Mods/
For example., if you download this kpop mod https://itch.io/t/481356/k-pop-mod-v10 you'll need to put folders Default and idolskins1.0 into the Mods folder