Do you have a question about the Areca ARC-5020-3 and is the answer not in the manual?
Discharge static electricity, shut down the system, and unplug the power cord.
Lift the rear latch to unlock and remove the side panel, allowing access.
Open the back panel latch and pull out empty drive carriers.
Loosen thumbscrews to remove the PCI bracket and port access cover.
Connect the card's cable to the motherboard and seat the card in the slot.
Re-insert the PCI bracket to secure the installed ARC-5020-3 card.
Slide all empty drive carriers back into their respective slots.
Slide the side panel down, close the latch, and reconnect external cables.
Connect the ARC-5020 RAID Box to the Mac using the e-SATA cable.