First you need to complete the Captain's Quarters quest and get the diver magic, which you need near the start of the Autopia Quest Track quest.
I am stuck on the part of this quest where you are supposed to earn 500 credits, btw, because I have read we are supposed to sell an Everest chair, but they lowered the value to 200, so what is up with that???!!! And I earned more than that in fireworks but apperently it doesn't count if you don't get 500 at once! Bleh, the only winners may be the ones who got through the quest before they lowered the chair selling price, so not fair!!!
Then after you get the car magic pin, I'm guessing, you can go on to the other room where you "get five credits" by driving around their track or something to win the license.
And then I guess you need the license for something else; I'm not anywhere near that stage.