How am I supposed to use direct monitoring on an interface without a "mix" button? (IXO22)

I recently got a new interface, the UR22MK3 (IXO22) and it has a button to activate direct monitoring. It doesn’t have a “mix” button though, or mixing software that comes with it so my question is:

Am I supposed to always turn down the master fader in Cubase if I want to be able to hear my vocals while recording? Or is there a better solution? (for direct monitoring, not in-DAW monitoring)

You shouldn’t have to touch the fader for monitoring. Are you using Mac or Windows? What audio driver? If it’s Windows w/ ASIO you can enable direct monitoring in Studio Setup and control your interface from the DAW; if you’re on Mac just leave monitor inactive and listen to the output from your interface while recording.