Any direct bus from HKIA to Longgang MRT station, how much, how long is the trip, frequency of bus?

Do you refer to Longgang Bus Station? If yes, you can take direct long-distance bus at the airport. The bus schedules are from 07:00 to 21:30 with the frequency of 30 mins. The duration is 2-3 hours. It costs 250 HKD per person. After arriving, the nearby metro stations are Nan Lian Station and Shuanglong Station, which belongs to Subway Longgang Line.