Any of Deezer's paid subscriptions will work, including the standard $10 per month Premium+ as well as HiFi, family and student plans. The app should be available in "most" countries where the Xbox One itself is available.
Deezer undoubtedly faces a tough sell for any would-be streamer who hasn't settled on a service, but the Xbox One app isn't strictly for them. It's more for those who are already invested in Deezer's ecosystem and might be tempted to switch to Spotify for the sake of Xbox streaming. Now, they don't have to choose -- it's just a matter of whether or not service-specific features (such as Deezer's automatically curated Flow stream) scratch their itch.