By this point, the characters have reached an age where dancing for fun doesn’t cut it, so they must find a way to make a living in the famously brutal field, whose humiliating auditions and frequent rejections make for a playful if out-of-sync credits sequence. It seems Sean (Ryan Guzman) and his crew, the Mob, moved from Miami to Los Angeles sometime after 2012’s “Step Up Revolution,” but now, they’re all late on their rent and decide to leave Sean to fend for himself in L.A.