Don’t know anything about Mac so I can’t speak to those issues, but...
...it looks to me like you have some redundancy here. The Zoom is a USB audio interface in itself, so you don’t need both it and the M-box. HOWEVER, since the Zoom has a headphone/line output, it could function as your mic feeding a signal to the M-box.I use a Mbox-2 for the output device, and I can play a clean, audible tone through it, but for input I want to use my Zoom H4n Handy Recorder (Mic Audio device), which can operate via usb
But either way, using the Zoom as your mic presents problems. Unless you have a calibration file for it, your measurements won’t be accurate.