I need a ticket from Hong Kong Airport to Central Station 16th and return 24th.

Well, for the round trip between the airport and Central Station, you don't need to buy the octopus card. Just purchase the AE tickets. Central Station is close to HK Station. Thus the AE Fare to/from HK Station is 100 HKD per person for the single trip.
Notably, the adult Standard Octopus Card will bring a lot of convenience if you travel around Central Station. For per card, the deposit is 50 HKD and the initial stored value is 100 HKD. And you can get your refund at the airport when you leaving HK.