You can cast from an apple phone or ipad to an Airplay device such as an Apple TV or some TV's support air play.
If you want to Chrome cast to a TV that supports chrome cast, you need to use to use an android phone to cast.

This is because our stream is web based, we don't have a native app (if we did that it would mean we would need to charge about 10 times what we do for the live stream).

So short answer, use an android device to chrome cast or an apple device to air play.

Toby