"Please place all markers on the character" and clothing problem

Hello everyone! I recently started Blender a couple of days ago and found myself to hit a wall. The model I chose doesn't seem have a lot under her dress. Mixamo asks for elbow and groin markers so I thought maybe it would work if I add objects as markers when the dress itself doesn't work. I'm unsure how all parts have to be attached together:

I have attached the clothing to the rig, which I think can be smoothen out with some weight painting, but I still find parts of the clothing stiff. At some point I clicked on viewport shading and boom she is pink. In the shader editor I still see the nodes and I'm not sure what I did for this to happen:

I've attached the imported model I found from our community and my own attempt to edit it. I also imported the gltf file from the game and converted it to fbx (this one has a groin). While it does work, the clothing is stiff and I don't know how to separate each layer.

I find myself starting over many times with each time getting slightly closer to get things working. 

Any help is appreciated 🙂