Below is the response from Deezer support. After attempting to control it through Connect from iOS to tvOS, I realized that it isn't functioning at all
Hello xxx
Yes, you can control the Deezer app on your Apple TV using your iPhone with the Deezer app on iOS. This is possible through Deezer Connect. Here's how you can do it:
1. On your iPhone, open the Deezer app and go to the player.
2. Select the audio options icon located in the bottom-left corner.
3. Select Deezer Connect.
4. Choose your Apple TV from the list of available devices.
Your music will then play from the selected device. Just make sure both devices are connected to the same Deezer account, connected to the internet, and the Deezer app is open on both devices.
For more details, you can check out this link.
Thanks,
Melodie