>>290401483
Did you use uTinyRipper to export the asset bundle?
They should work natively within Unity, you might have to update your tool though.
That tool exports in a format that the Unity editor can read natively. (So if you're extracting an asset bundle you've downloaded it should clearly work)

I wouldn't recommend using Asset Studio since you won't get a format that you can reuse within Unity.
However if you don't care and just want the model to work on, the fbx is fine.