Uploading an avatar to cluster
In this guide, I assume you already know the basics of Unity and probably have previously uploaded an avatar to VRChat. If you haven't, you can still try to follow along, but some descriptions might be a bit too brief.
You need Unity 2018.1.1f1 and the cluster. SDK. In the Player Settings found inside the Build Settings, set the Scripting Runtime Version to .NET 4.x Equivalent before importing the cluster SDK.