If you are talking about VRchat:
Stand inside your t-pose avatar so your spheres line up with where they should be, same with your hands and head, then click both triggers to “lock” the avatar onto you.
EDIT: You need to move using the touchpad/stick once after locking for it to start working.
It seems to lock tracked points onto the mesh, so if the t-pose model has its feet very close it can be very hard to get it right.
I thinks thats because of how VRchat binds to trackers and not because of the driver.
Havnt tried this yet but if one can get a model to work when imported and has its feet spread a bit, locking onto it might be easier.
Another thing would be to talk to the VRchat people and understand exactly how it works.