This avatar was created for VRChat and has an industry-standard rig. The “Additional File” download includes the unitypackage containing the character - Unity3d 2021.3

VRChat: If you use this avatar for VRChat, it is suggested you use the Poiymomi toon shader library: https://github.com/poiyomi/PoiyomiToonShader/releases

Mixamo: Mixamo will recognize this rig and auto-assign animations to it without a problem. https://www.mixamo.com