No train from HKIA to Disneyland. It seems not free to the theme park. It is a package that the hotel offer. You should inquiry about the offers when you book the hotel. Disneyland is far from Ocean Park, about 1.5 hours on the way there. You should take MTR from Disneyland to Admiralty after two shifts, then take Bus 629 at Exit B of Admiralty MTR Station. 20 minutes later, you will arrive Ocean Park.