I stream iTunes (Mojave) to an Apple TV gen 3, which has toslink, into a DAC.  
I made  a folder in iTunes and added radio stations ( Internet Radio, listed in library from iTunes ).
This feature is not available in the new Apple Music (Catalina) which replaced iTunes.
Can you download the last version of iTunes into Catalina and proceed as before?
To stream a radio station from its website requires using Airplay which is not desirable. Plus, can't easily 
choose from, say, 10 different stations. 
09f118d5 0302 48c2 94f4 773faa506010jackiejr

I haven't yet upgraded to Catalina but I've found this solution to your question. Hope it helps. Thanks for asking it because it will help me once I upgrade.

Good luck,
I'll give it a try and report back. Thanks Tom!!!