Style creation IS hard, period!
There are instructions in the book (sometimes fathomable!) and some excellent on-line videos that will tell you what buttons to push in what order, and that's fine.
Alas, there are no instructions in the book or on line that will magically give you the musical skills required to produce a really good musical style! You need to understand arranging, you need to think like a bass player, drummer, guitarist etc and how they would actually play. You need to think about arranging correctly for strings, brass and reed sections. And so on! And then you need the skills to take all of that and relate it to what you have to do on the keyboard. I'm lucky, after 50 years as a pro and a teacher, I do have all those skills - some sharper than others - but I'll still leave style creation to the experts. I might edit a style now and then, replacing a bass line or rewriting a poorly written string section perhap, but I don't have the time or inclination to go from scratch!
But registrations are easy, and if you have a keyboard that allows you to set up your own registrations, then I'd encourage you to do it. There's a foolproof guide on my website!