There is no special problem with shift/CTRL/Command zoom on Mac.
Just remember that it does not work in Fullscreen. This is same for all viewers.
It only works in browser window.
What makes some people believe that it does not work is that they forget to click in the pano first.
This is same for all viewers and also both for Windows and Mac.
There is a difference on Mac that zoom out works both for CTRL and Command key.
Hans