Taxis can take you directly from the airport to Robert Black College on University Drive for about HK$400.

The Airport Express train costs about HK$100 each way, although slightly cheaper tickets can be purchased from the travel agents in the airport (about HK$80 each way). The Airport Express will take you to Central on Hong Kong Island and from there you can catch a taxi to Robert Black College.

Further information can be found at –
https://www.hku.hk/maps/pop_maps.html?section=mc
https://www.hongkongairport.com/eng/transport/to-from-airport/airport-express.html