GEP is the default Addon Pack for FVTM.
It contains some essential parts and materials.
Unless you have other packs providing FVTM materials like keys, impacts, canisters and parts like engines, you should install this pack.
FVTM packs get installed into the /mods/ folder on 1.20.1, they are not a mod by themself, FVTM handles all content loading and registation.
