I am having some issues now with creating my own CC for Sims 4 from the bottom up... I tried using a tutorial to create furniture and got this monstrosity that won't obey anything I want it to do in Blender. This is difficult. If anyone knows how to fix my issues with the shading not being able to be change/adjusted or with the wrapping, here is the file.

chair base2.blend

If someone would take a look and tell me exactly what I need to do, that would be great.