FBX wont upload to mixamo "Unable to map your existing skeleton"

I have made a very simple model in blender which doesnt seem to have any problems, geometry is fine but for some reason i keep getting this error , when i export as an obj it works fine but i can no longer apply textures to it, its just the default grey, and last when i attempted it as a .zip it messed up the textures, ill link below the FBX file that im using