Sadly, I don't think it works(it just doesn't appear in avaliable outputs), and I couldn't find any docs that might explain how/if I could make it work.
Instead, You might be interested in new SC option that allows to show anything inside your osu! window (ingameOverlay - examples in my previous post) -that should be released later today nvm having huge issues atm(obs pls).
Instead, You might be interested in new SC option that allows to show anything inside your osu! window (ingameOverlay - examples in my previous post) -