According to this, Chick gave them the rights.
Ralls had hoped to make a film of the comic in college, but the project never came together. This time would be different. Armed with his winnings, Ralls wrote to Chick, asking to buy the rights to Dark Dungeons. “Dear Mr. Chick,” he wrote, “I won the lottery … I have decided that the best use of the money I won would be to film and distribute a live-action version of your tract ‘Dark Dungeons.'” To Ralls’ surprise, Chick responded—and offered the rights for free.
Thanks for linking that. It was a great read. I'm definitely going to track town that movie now.