Arrived at HKIA at 2000 hrs. How do I get to Jiuzhou Ferry Terminal, Zhuhai from HKIA ?

There is no ferry at the airport that can take you to Jiuzhou Ferry Terminal at that time.
You can take airport express to HK Station, Exit E1. Then walk to Hong Kong-Macau Ferry Terminal. There is a ferry at 21:30 that get to the destination. The ticket fare is CNY 175 per adult. And it takes 75 mins on the way.