How does the city glider work?

I have to travel around Brisbane for work and I’ve been using the TransLink app to plot routes. I’ve had options pop up for catching the city glider to another stop but I’ve always decided to take another route. Today it would have been easier to take it but when I got to the bus stop it said it was pre-paid and the council website says the same. Does this mean I have to buy a ticket online or can I just use my GO Card?