HomePod Automation for playing radio stations

When I bought my new Mac a few months ago, I signed up for a six-month subscription to Apple Music. I hadn't had it before, and to be frank I hadn't really needed it. I set up a handful of automations to play RNZ National Radio, to come on half an hour before I get up in the morning. Additionally we get Siri to play it and generally, as long as the RNZ/TuneIn connection is working properly, that's worked fine.

Until now. I didn't continue the Apple Music subscription because I wasn't using it. The automations still work(!) despite it, but I can't add more automations, nor edit the ones that exist. Neither can I call on Siri to play it: "I can't find RNZ National in your music library". I'm not going to renew my subscription just to play the radio. There has to be a better way. What has changed, because it worked well last year? How can I get around it?

Laurie