I just showed them the pamphlet I got in the mail along with my luggage tags. They scanned the bar code on the back a couple times and confirmed the number of people in my party. They direct you to one of several lines for different buses and scan that pamphlet a couple more times and then I got on the bus.
I saw some people waving their magic bands in front of a reader but I don't know if they also had their pamphlet scanned.