How to configure the Beryl AX as an access point with the Brume 3?

I'm going to connect the Brume 3's WAN to my ISP-issued modem. Then I want to connect the Brume 3's LAN to the Beryl AX's LAN for WiFi that will be located in another room.

How do I configure the Beryl AX so that it will act as an access point? Are there any privacy and security hardening policies I should be aware of when configuring it?