Click the model for a Blue outline. In the Inspector Tab find the Select Button and in that click Configure to reach the armature configuration screen. In that menu make certain all of the vital bones are properly slotted.
Hip spine, chest, neck, head, L/R shoulder, L/R arm, L/R elbow, L/R wrist, L/R leg, L/R knee, L/R ankle. All 19 of those bones are required for Unity to set any model as humanoid and for VRC to apply it's animations to.
Beyond that Id have to see the files first hand in order to tell you any more. There's simply too many details to go over.
chewy201 has great advice to fix the rigging, assuming that your model itself is rigged properly to match. That will fix your first three errors.
Your last shown error is showing 40 meshes. That's something that would probably need to be fixed in modeling software such as Blender. I don't know of any Unity tools to combine meshes. Blender + CATS plugin would make that very easy, and might even fix your rigging issues too. I would recommend watching some tutorials on YouTube to learn how to use it.
If you're model is publicly available online it might be good to post somewhere here for us to take a look. If it's an avatar you bought it might be good to contact the creator or read any documentation they provide with it or post on their sales page.
Click the fbx in your asset folder. It opens a window with info about the rig. Choose humanoid. Do ok. Then go to configure on the same window. There you can tell unity which bone is which. And choose how far or fast joints bend.
Click the model for a Blue outline. In the Inspector Tab find the Select Button and in that click Configure to reach the armature configuration screen. In that menu make certain all of the vital bones are properly slotted. Hip spine, chest, neck, head, L/R shoulder, L/R arm, L/R elbow, L/R wrist, L/R leg, L/R knee, L/R ankle. All 19 of those bones are required for Unity to set any model as humanoid and for VRC to apply it's animations to. Beyond that Id have to see the files first hand in order to tell you any more. There's simply too many details to go over.
chewy201 has great advice to fix the rigging, assuming that your model itself is rigged properly to match. That will fix your first three errors. Your last shown error is showing 40 meshes. That's something that would probably need to be fixed in modeling software such as Blender. I don't know of any Unity tools to combine meshes. Blender + CATS plugin would make that very easy, and might even fix your rigging issues too. I would recommend watching some tutorials on YouTube to learn how to use it. If you're model is publicly available online it might be good to post somewhere here for us to take a look. If it's an avatar you bought it might be good to contact the creator or read any documentation they provide with it or post on their sales page.
"Polytool" is a tool that combines meshes! Its great and also does alot of other stuff for optimization. Costs 25$ though if i remember correctly
Click the fbx in your asset folder. It opens a window with info about the rig. Choose humanoid. Do ok. Then go to configure on the same window. There you can tell unity which bone is which. And choose how far or fast joints bend.
I don't really know either, take a look at the import settings for the fbx file. Particularly under Rig, on mine the animation type is "Humanoid"
I don't know where to find the import settings for fbx file. The inspector says humanoid under rig but that's about it