Which OS X version are you using?
This could either be a rights problem, or a new issue in PortAudio. Do you know if other USB sound cards work?
I just remembered that I have two macs with different os versions. I'll check back to see if there is any difference in behavior.
I did some testing. On Mac Big Sur 11.3 it works like this:
With ST 9.62: Webstation (usb) works, virtual sound cards do not. Additional test: Logitech webcam (usb) microphone also works.
With ST 9.70: Webstation (usb) does not work, virtual sound cards do. Additional test: Logitech webcam (usb) microphone also works.
On Catalina 10.15.7 I have not been able to do a test with the Webstation, it is at a different location. Other than that, the same behavior when it comes to the virtual sound cards.