Loading Custom Avatar rigged from Mixamo
Auto rig your custom model in Mixamo, the model must be 1.6 to 2 meters in height
Go to the menu
Click the GLTF icon - to upload your Mixamo rigged Avatar
Select the GLTF file, (Must be in GLB) binary format embedded with the texture
Upload
In the GLTF menu select Avatar, then click the Load button