As stated below, the Hubitat does not wireless receive WiFi signals. All WiFi signals are through your router. It is possible for the Hubitat Hub to communicate with WiFi signals (again through your router) however this is very uncommon.
The Hubitat radios communicate wirelessly with Z-Wave devices and Zigbee devices. A contact sensor will easily communicate with the Hub when in the next room. I have Zigbee devices in my garage with the Hubitat hub located 2 rooms away.
My best recommendation is to simply try it before the actual installation.
At some point you will exceed the capability of a device to communicate with the hub due to distance. In these cases you can put a device (that is always powered, like a wall switch) between the hub and the distant device. The signal can now go from the hub to the switch to you device further away. These devices are called "repeaters". Repeaters must be the same technology as the distant device.
i.e. For a zigbee device the repeater must be a Zigbee repeater
and for a ZWave device the repeater must be a ZWave repeater.
Not all devices that are powered by the mains are repeaters or sometimes poor repeaters so if you find you need a repeater post and ask folks for a recommendation.
Hope this helps.