In the Artstation images, (and in the post...), there is a model in position "A" (If you can call "this thing" with 4 arms that...)
With that it is possible to make a rigging. With this model with arms crossed at the pelvis, it is impossible. There are hidden polygons, and deforming the mesh would be a disaster.
The weapons and clothing can be separated, as I have seen in Rhinoceros. They can be adapted in Marvelous Designer to make a "garmet" d-force...
In Max, the idiot from DesireFX_com with his disgusting habit of modifying the names of things that are not his (Even the groups of polygons.. He is a total jerk.)
The fbx is ridiculous in size.
Without pose A, there is nothing to do.