I think it's vital to learn to do them manually first. MD is a fantastic tool but there's no guarantee you will have access to it at every job and the best artists can do both.
Actually, learn to sculpt folds manually first so you understand flow. Once you are proficient, switch to marvelous. MD is never going to give you a 100% usable item...you need to be able to take that and go into zbrush to refine and add folds that work for your specific item. For your cap, have as much reference as…