Connecting Promethian Screens to WiFi

Hi All, new to the fortigate/FortiAP world so needing some help on a few issues

We Have recently installed a new Wifi network into a school using the fortigate being used as a wireless lan controller and the APs are the FortiAP241k models. We are trying to connect a device which is a large touchscreen television to the network and it does not authenticate and can not connect to the wifi.

The device is a promethean Active 9 device. We have tested the screen by connecting them to a personal hotspot and these work fine so it is just the fortigate Wifi it can not connect to. We have also tested plugging the devices directly into a switch port and these work fine this way also.

Is there anything we need to do on the fortigate to make these connect to the wifi and is there anything that would be stopping these devices connecting.

We have also tried to screen share from a laptop and an iPad to the screen when they are on the same network and this also does not work. Like the above issue is there anything we need to configure to make this work? 

here is a link to the screens <link redacted>

if anyone can help that would be fantastic