Unfortunatley Apple TV is not supported for use with the Virtual app. 

Apple TV is great for home usage, but in a business environment, there are many things that can compromise the video experience: WIFI signal and strength Connection to the wrong WIFI AppleTV video compression

Because there are so many additional areas for things to go wrong, we have settled with HDMI as a more reliable and higher quality connection for the Virtual High Definition video and audio

HDMI cables While good for short connections, standard HDMI cables are not designed for long lengths and we have seen many installations suffer reliability issues, some after just 6 months. As a result, all have replaced the HDMI cables with better quality technology. We recommend using good quality HDMI cables that are less than 5 meters in length

For a reliable long run cable alternative, try HDMI over ethernet. There are many manufactures offering transmission boxes with the technology able to send HDMI reliably beyond 70m with premium manufacturers. Consult your AV partner for a recommended solution

Recommended: Kraemer PT-571 & 572+  HDMI over Twisted Pair Receiver / Transmitter with EDID pass-through https://www.kramerav.com/product/PT-571