Are you importing the right thing? I don't really know much about cc but I'm p. sure the thing you have to export in order to recolour is the thing called "diffuse" on sims 4 studio. It's under where it says texture (you have to select your project first before you see this.) The diffuse thing does look super weird not in colour but in shape, but you should still be able to understand what part on the diffuse thing corresponds with what sims body part. I.e I recoloured a tshirt and in game it looks like a tshirt but the diffuse layer looks like this:
https://i.imgur.com/iEaYZW5.png
And that looks weird but it's nothing to worry about, it will still look like a shirt if you recolour that. It's probably best to choose the lightest swatch to recolour though, I've never actually recoloured more of just put smth on a top that wasn't there like the logo on the top in my pic.