Hi Lorenzo,
ZF7731 is an 5ghz bridge device with directional smart antenna and got 30° beamwidth and NOT be used as an AP for servicing wireless devices as its usual use case is to be deployed to easily extend branded broadband services, backhaul 3G networks, offload data traffic from 3G networks, deploy multimedia hotspots, or offer wireless broadband services where fixed line access is limited
Having said the above, technically ZF7731 root bridge is an AP which allows non root bridge to connect as a client. Now if you want to connect a Laptop or smart phone to connect to it then i would say its possible however ZF7731 is not right product for client connectivity and will have limited sucess due to its 30 degree beamwidth and 5ghz radio only.
hope this helps.