It can.
Most of the settings are in the wired port profile applicable in your AP group (under the interface number sub-configuration). You should be able to set the "Forward mode" to bridge if you simple want the RAP to bridge the port straight to the ADSL router (or flat LAN). You'll also see other settings in there in case you want to get more complex with it. Under an AP wired port profile, you can also apply a firewall role to the connection if you like.