Get Plex to play a song / album to amazon echo device

Hello, every time I try to call media_player.play_media I get this message from my echo:
“Sorry, text to speech can only by called with the notify.alexa_media service. Please see the alexa_media Wiki for details.”

I have the Plex integration setup. Whenever a device is playing media it shows up in HA.

No idea what’s going on.

I’m simply trying something from the examples from the docs regarding the plex integration (updating for my own library name/music/album, etc.

entity_id: media_player.echo dot
media_content_type: MUSIC
media_content_id: '{ "library_name": "Music", "artist_name": "Adele", "album_name": "25", "track_name": "Hello" }

Thank you!!