Anything else aside, I’m pretty sure the current Metahuman Creator is not even finished, much less meant to be a standalone, one-size-fits-all solution. It’s labeled a “preview”, after all, and more than a few of the hairstyles note they don’t have assets for anything other than LOD0.
Most folks I know using Metahuman Creator right now in a preview state are generating assets which they then either alter in Blender or Maya, or where they’re taking the head (or even just the hair!) to put on character models generated elsewhere.