Sounds like your needs might be best met with a few discontinued Chromecast Audio pucks. Getting my WiiM Pro Plus up and running was/is a slowish process for me. I would do as Brantome indicates, using one of the in app radio streams to confirm the WiiM will give you audio out. Then you can move onto other functions.
I got mine working this way, then got frustated because I connected a CD player to Line In and saw the light go green which meant I had chosen that input so why no sound? I fumbled my way around the app and eventually saw that the WiiM input was on Bluetooth, not Line In. When I switched it to Line In, sound from the CD player. Later I discovered the automatic input detection default is set to off in the app.
There have been other quirks. I am still learning how it behaves. The app may be much better than other apps out there but on an absolute scale is is not Primo.
I give WiiM huge credit for their integration with Alexa. The WiiM is so far behaving exactly the same as my Amazon Echo speakers.