Really funky automatic weights

I have a hand mesh from the oculus quest demo files and a basic rig that I’ve constructed. After attempting to parent the mesh to the armature with automatic weights, the bones have terrible automatic weights that are all over the mesh ( pointer finger bound to vertices on the ring finger, etc. ). I have attached the blend file used. How can I fix this so that the automatic weights are better? I’m not sure what I’m doing wrong.

Blend file:

Incorrect automatic weights: