[Volusonic] connecting to and streaming from Nextcloud

Hi! I have troubles with (-> see headline>).
I have some music at my nextcloud server, and there is a plugin for subsonic compatible player ( https://github.com/owncloud/music )

And I am looking for a way to stream this audio from nextcloud to a hifiberry. I thought volumio can do it, as there is a subsonic plugin. So I just testing it, booted it up in a virtual box, installed the plugin… and… not working:

I don’t see any logs that would help me help myself :confused:
Is that possible?
Thanks!
PhiL