I think it doesn’t support actually streaming content to devices at the moment - there’s been an issue related to this for several years that’s also listed in the README. Its networking is also a bit of a hassle to set up.
I think aethercast (which the Ubuntu Phone uses) might be more promising.
In the meantime GNOME Network Displays works OK, and in spite of the name doesn’t require much of GNOME, the only inconvenience is getting it working with your firewall.