Lowering polycount for LODs and clothing mesh issues

Hi there,

Please could I have some assistance. 

I received this rejection message from TSR:

• "CLOTHING Lower LOD meshes not lining up with body

The meshes of your medium and/or lower LODs are not lining up correctly with the rest of the body. This can happen when you use a poly slider on your high LOD mesh to make the medium and low LODs instead of making use of the original medium and low LOD body parts."

• "CLOTHING Reducing polycount lower lods

The polycount of the lower lods of your creation are not reduced enough. Please reduce them to such a level where the lowest lod has a maximum of around 3000."

Firstly I have no idea what either REALLY mean. I used the poly slider in decimate in Blender to make lower LODs following a tutorial. But apparently that isn't right if I am understanding correctly. I actually have no idea what the first one is about.

Secondly, how do I reduce the poly count without starting all over again? I have seen download things such as Instant Meshes Remesh but I can't understand how to download it.

How do I fix either of these problems?

Here are the files I submimted:
www.dropbox.com/sh/g3eoia65wtova3h/AADLlzN0FcMMGhY_OT-PfpQBa?dl=0

Thanks! This is my frst mesh, so it has been a journey