Spotify and Chromecast

Hello to all,
I’m new to HA and I’m trying to connect Spotify to my Chromecast to start a playlist in the morning as an alarm clock.
Spotify is connected properly and Chromecast also but I can not get a playlist on the Chromecast to play by changing the source.
On my mobile phone I can see the chromecast between “connected devices” but when I set “source”: “TvSmartGoogle” in HA does not work.

Some idea?