It does work, I once had a connection to one with a UR22, but this person was unexperienced and I couldn’t look at the persons screen.
We had some problems with it, but since we didn’t really try to solve them, it might only have been a user error. And this was under Windows.
As far as I can remember the network buffer needed to be set to 512 which leads to a larger latency. But this was half a year ago when I started experimenting with soundjack.
Check if you need a driver for the Macintosh at all. If the interface is visible under the Audio-MIDI-Setup app, you don’t need a driver when connected (and powered up which might take place over the USB conector). If it’s not visible (under the Audio tab), check if there is a driver for your version of MacOS X available, install it and best restart the computer. After that it should be visible selecting the Audio tab of Audio-MIDI-Setup.
Then I would recommend starting with [sample buffer / network buffer / jitter buffer] set to 512/512/1, if it works reduce to 256/256/2, then 128/256/2, then 64/256/2. Then use the latest working one and try to reduce the jitter buffer from 2 to 1. (Assuming that both partners are rather close together, otherwise a higher jitter buffer number might be needed.
Using external interfaces is easier with a Mac than with a Windows machine as long as it works with the class compliant driver of OS X (built-in) or a special driver for your interface that is compatible with the operating system version of your operating system.
In general only older interfaces or interfaces with more than four (or sic?) channels need a special driver to work with a Mac, but it also depends on the version number of the operation system.