Configurate Mac/Apple TV for Classroom

I am attempting to connect Apple TV in my classroom to our network. The only way we can is to use the configurator. I installed configurator, plugged in the Apple TV to my MAC and attempted to configure the device (per the written instructions). It does not appear to be reading the device. It has "attach device" - but the device does not show up on the screen. Could someone help me. School starts in three days, and I will have no time to do this then!