The Bier Festival is a separate, ticketed event. You have to buy an add-on ticket in advance when you buy your fireworks ticket. 

You have to buy a ticket to the fireworks Festival to enter the park. At the time of purchase you can then add on a Bier Festival ticket. The Bier Festival can be accessed via the Palm Court entrance.

Please note the Bier Festival is for over 18's only. The bars operate a Challenge 25 policy.