GEP is the default Addon Pack for FVTM.
It contains some essential parts and materials.
1.12.2 -> Forge
1.20.1 -> Forge
1.21.+ -> Fabric
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.
