I am glad you like it. The hero-driven story is where the hero, or protagonist, is the catalyst or reason for the story or the events that occur in the book, instead of the a villain. One example I can think of is the first Pitch Perfect movie. Beca goes to college and meets a group of girls that want to win the A capella competition that has always been there. There are no real villains or protagonists. Yes, there are opponents, but none of them drive the main story forward or really challenge them as a central theme. The girls want to prove that they are the best, and are the main driving force towards the end of the story.

I haven't read or seen the Dark Tower series, but if Roland is on that quest for his own reasons, and not because a villain or someone else drove him towards it, then yes, that would be a hero-driven story.