Roon core organizes your streaming services and local music files.
Depending on your core computer, it will output digital music over Ethernet, or it may include an onboard DAC and output analogue.
typically roon core resides on a computer or roon nucleus computer, on your network.
your node is both a streamer and a DAC. It can output usb digital music to another DAC, or it can output analogue.
if the DAC (roon endpoint) is roon ready or tested, the endpoint will show up on the roon interface and be selectable.
I have never used a non roon ready DAC, but I believe it will work fine from your usb output of your roon ready node streamer.
hope that helps.