In case it confuses you. In unreal uv channel 0 is channel 1 in 3ds max, and channel 1 in unreal is channel 2 in 3ds max. You should have the first channel there even if you haven done any manual unwrapping. But seeing your other message you might have figured all this out by now 
Also, try to set the light map resolution higher to get better lightmap bakes if you got some weird shading or similiar things going on. Also, go back to the lightmass/lightmass documentation and re-read that a few times so you understand when you can do the automatic unwrapping for channel 2 (which is usually 9 out of 10 times), and when you need to do some manual work on your unwrap.
You find the resolution for the lightmaps in the details panel when you double click your mesh in unreal. Test with power of 2 values: 16-128-256-512 etc.