M4 never had an official dev rig released, so you have to create your own. There used to be one available at rdna I think, but...

Don't enter the setup room with a figure that's already rigged. It can break things and you're just asking for trouble that way.

Instead load a new M4 and open the hierarchy editor and check the box that says 'show all parameters'. Then delete everything you see listed under M4 that is not a body part. All morphs, magnets etc. Then go into the material room and delete all materials. Then save that empty rig back to your library as a dev rig and you should be good to go.