Sign up is free, and you can add points by doing things like buying tickets to their theaters. You can redeem your points for things like free popcorn or movie posters, but they also offer some "freebies" that require no points. That includes free digital Comixology comics from Star Trek Starfleet Academy and Ghostbusters!
You can sign up for the Regal Crown Club by clicking on this link. You can get the free Ghostbusters comic by clicking here. You can get the free Star Trek comic by clicking here.