Yes! The Big Bash Premium Track is a purchasable option for you to earn even more prizes by earning points during the birthday event. If you have Premium, you will automatically have access to the Big Bash Premium Track; if you don't have Premium, you must purchase a Big Bash Premium Track Pass in the NC Mall. Once a Big Bash Premium Track Pass has been purchased, it will automatically apply – it will not go into your inventory!
Note that while the Big Bash Premium Track is free for Premium players, if your Premium Subscription ends during the event you will no longer be able to progress along the Premium track without renewing your subscription or buying the track pass from the Celebration Pass page.