Luke Stephens modeled the springtail body in the 3D software Blender.
The virtual skeleton that activates the movements of the avatar is placed inside the springtail model. The Humanoid Controller for VR had to be adjusted to fit into the springtail body, but the extra set of legs really caused the whole body to malfunction. So Luke had to redesign the character. The new character also has hands, which is not realistic to springtail insects, but since it is a part of the Humanoid Controller they were included.
Though compromises had to be made to get the avatar to work in VR, this is expected. The very idea that humans can understand what it is like to operate the body of another is fraught with challenges. There are always approximations and best guesses.