You will need this licence if you intend to operate a major amusement park. A major amusement park is a workplace that has at least 4 amusement devices, including at least 1 class 3, class 4 or class 5 amusement devices under AS 3533.1, or a high structure water slide at least 10 metres high.
If all the rides at a workplace are for a temporary event (such as an agricultural show or school fete) it is not a major amusement park and does not need this licence.