Connecting Chorus ONT Type 300 to ASUS DSL-AC68U Router

Trying to help out my daughter's flat here. I'm not there so can only pass on your advice. They've just had fibre installed and didn't take the option of a modem from the ISP as they have an ASUS DSL-AC68U Router they hoped to connect directly to the ONT. However, they can't get it working. I see that the ASUS DSL-AC68U is a ADSL/VDSL modem router without a LAN port. Some points that come to mind:

I understand that only LAN1 of the ONT can be connected

Does it need a modem and if so then what spec's?

Or does its LAN1 port need to be connected to a WAN port of a router? If so, what should the WAN settings of the router be?

Or does it have DHCP and can it connect to a switch?

If it has DHCP, then I presume the DSL-AC68U could be configured as a switch and access point but have not looked that far yet.