Loopback function might do what you want.
I’m on Windows. When I want to record computer audio I need to set the UR44 as the default playback device so that the computer audio is actually playing back through the interface. Then I turn on Loopback. If set up correctly you should see (and hear) the computer audio on channels 1 and 2. (UR Mix1 L and UR Mix1 R).
You probably want to use those as input in Machine.
Be careful not to create a feedback loop.