Quick fix for armature / rig issue in Blender ($20 to provide / explain solution)

Quick fix needed on this Blender model. Issue with a custom rig created in Blender. https://drive.google.com/file/d/1LoEbuEF8Own63fXieiqXFntlqMx-6C21/view?usp=sharing Issue: model is not deforming with the armature after parenting the mesh to the armature (with automatic weights... (Budget: $10 - $30 USD, Jobs: 3D Animation, 3D Design, 3D Graphic Design, 3D Modelling, 3D Rigging, Blender)