FBX Workflows Overview

There are 3 different types of FBX workflows in 3ds Max

Biped-Originated FBX to Biped

This video is an overview, check more on following chapters
If the FBX was exported by 3ds Max Biped(BIP), you can directly convert it back to Biped again without mapping process.
Workflow: Mapping Character -> Biped-Originated FBX to Biped -> Copy Animation/Weights -> Import Animation

Non-Biped-Originated FBX to Biped

This video is an overview, check more on following chapters
If the FBX was exported from any other arbitrary rig but not 3ds Max Biped, you need to first set up mapping and resume it to T-pose.
Workflow: Mapping Character -> Resume T-Pose -> Non-Biped-Originated FBX to Biped -> Copy Animation/Weights -> Import Animation

FBX to Bones

This video is an overview, check more on following chapters
This tool can convert any FBX to 3ds Max bones system. It works with arbitrary creatures including non-humanoid ones. We need to map every root bone in “Others”(accessories) tab in the mapping window.
Workflow: Mapping Character(only accessories) -> FBX to Bones -> Copy Weights -> Copy Animation