I am going to land on Sunday at 15:25 with luggage. I will need a ferry from HKIA to Zhuhai

The procedures are as following.
Flight Arrival – Purchase ferry ticket and present baggage tag receipt at the Ferries to Mainland Ticketing Counter at Transfer Area E2 – Scan ferry ticket and check your baggage status at the ferry boarding entrance – Board the Automated People Mover to Skypier – Board ferries to ZH
When you arrive, you can follow the signs or ask staff for help to get to the port. The port’s name is Skypier.