How many laps do we have to complete before you win?

@Diana-P there are no set laps, you just keep going until the race ends and winners will be determined by where you are at the end. Once you complete lap 10 node 5 even though your numbered laps are increasing you are just doing lap 10 again and again and again.

@Diana-P It is all explained in THIS THREAD,

There are also pop ups when you log into your game as well as instructions within the event that explain what you MUST do to get the dragons available in this event. All you have to do is read what's there.