AirPlay 2 has not yet been implemented, it was deleted from iOS 11 beta 5 and will be coming to a future update of iOS 11. They may be giving hardware makers time to update their firmware to be compatible? (I was wondering why I could not find any support articles on this on apple's support site.)
"At present, not only is Messages in iCloud not fully implemented, but Apple Pay Cash and AirPlay 2 appear to be missing as well."
Messages in iCloud not implemented at present, coming in a future update to iOS 11
http://appleinsider.com/articles/17...t-present-coming-in-a-future-update-to-ios-11
Inside iOS 11: AirPlay 2 on existing speakers requires firmware update, support for Apple's AirPort Express unknown
http://appleinsider.com/articles/17...-raising-questions-for-apples-airport-express
Apple's AirPlay 2 not currently functional in iOS 11 devices connected to tvOS 11
http://appleinsider.com/articles/17...tional-in-ios-11-devices-connected-to-tvos-11
"At present, not only is Messages in iCloud not fully implemented, but Apple Pay Cash and AirPlay 2 appear to be missing as well."
Messages in iCloud not implemented at present, coming in a future update to iOS 11
http://appleinsider.com/articles/17...t-present-coming-in-a-future-update-to-ios-11
Inside iOS 11: AirPlay 2 on existing speakers requires firmware update, support for Apple's AirPort Express unknown
http://appleinsider.com/articles/17...-raising-questions-for-apples-airport-express
Apple's AirPlay 2 not currently functional in iOS 11 devices connected to tvOS 11
http://appleinsider.com/articles/17...tional-in-ios-11-devices-connected-to-tvos-11