I'm not super familiar, but it looks like you're subscribing to Roon's metadata but it's "bring your own music" (to quote their FAQ) which can be files you self

I'm not super familiar, but it looks like you're subscribing to Roon's metadata but it's "bring your own music" (to quote their FAQ) which can be files you self-host and/or supported music streaming services (which don't include Roon) that you subscribe to separately.