Since I already have Google Assistant Relay working, I found this a bit more involved then I needed.
If anyone is looking for an alternate choice, I instead downloaded the latest nightly for MacOS VLC Player 3.0.4 which is able to Cast and have the HTTP web interface active at the same time.
NOTE: To get this working, I found it was necessary to first disable the HTTP web interface then quit and restart VLC Player. Once it's running again, set the cast device, and then go into the preferences and re-enable HTTP web interface.
Works great, and I now have both my door chime and a verbal announcement of the door that has been opened.
[Edit} I forgot to include something I did previously, and for some time couldn't get this working again. There's an important step after re-starting VLC Player, selecting the Cast device, and then re-enabling HTTP. You then must then go to the VLC menu, choose "Add Interface" and select "Web". It should then work to play a track from Hubitat.
