My understanding is that they test you at the airport, where you wait for results, and if negative send you to mandatory 14-day quarantine. Not sure if this is still allowed to be at home with tracking bracelet, or is at a designated center, or at a hotel you have to pay for (actually I think regardless you probably have to pay for it). If positive, you go to whichever hospital they send you to.
Note that the Centre for Health Protection website (
https://www.chp.gov.hk/en/index.html) has details. They also have numerous news releases of mandatory prison sentences imposed on people who broke quarantine.
