How do I Chromecast new Android Apple TV app?

I installed the new Apple TV app on my Android phone because I wanted to Chromecast it to my TV, but for some reason I can’t make it work.

I don’t think my phone is broken. Netflix Chromecasts from this phone, as do Mubi, Prime Video, Tele2, Viaplay, Youtube, SVT, TV4 and every other video streaming app I’ve tried, EXCEPT the new Apple TV one. I have tried using Chrome on my PC to Chromecast Apple TV but it’s so clunky I’d rather not!

How do I get this “from the ground up” Android app to Chromecast? Thanks in advance to anyone who can help!