If you check in on-line make sure you have a hard copy of your BP. I've tried to go airside with an electronic copy and was refused.
Fortunately, I had saved the BP on my thumb drive and found a place in the check in lines (D?) that could print it, HKD$10. With the hard copy I went straight through and could access many different lounges (WP).
Oh and consider enrolling in the e-Channel service to go through immigration easily at HKG AP
https://www.immd.gov.hk/eng/services...html#australia
How long ago was this? It’s not the case anymore.