It needs to function as a DLNA renderer. And then you need to use the generic speaker custom code device type handler, not the Sonos device type handler.
See the following topics (the topic title is a clickable link)
This Smart App and device type allows you to use any DLNA Media Renderer to receive Sonos-like sound and voice notifications from SmartThings.
You must to install the MediaRenderer_Connect to find any Generic Media Renderer (Network Speaker)
The MediaRender Player is the device type needed to control each Media Renderer.
If you dont have a Media Renderer like Smart TV or Network Speaker with DLNA you can test it with Foobar2000 program installing de upnp commponent. The commponent allows you to convert the player in a Media Renderer (Verify your firewall do not block the foobar2000 port )
I have tried some Media Renderers, but is better if you give me a feedback of the models that works for you.
Tip : Please, just install one time the MediaRenderer Connect from the phone, If you have…