Unity: https://docs.vrchat.com/docs/current-...
VRCSDK: https://vrchat.com/home/download
Avatars: http://gumroad.com/vr_zab
Multiple versions of each Avatar in the scene:
-HighPoly/LowPoly for PC
-LowPoly/Fallback for Quest
Depending on which one you upload (hide others), you can choose your avatar ranking (Good/Medium/Poor) depending on how high-poly or fully featured you want your avatar to be! Quest has strict limits so my Quest versions are usually lower poly by default.