Well, yes, the right mouse button is set up correctly, it works fine. The problem is with emulation of the right mouse button by ctrl-left. Ctrl-left on the desktop does nothing when Emulate right mouse button is checked.
On the Mac, ctrl-left works fine, same as right click. I am not aware of any key mapping changes.
On the remote Linux machine, I had assumed that this was a generalized problem, but it turns out that it is only on the desktop that the problem appears. Ctrl-left on the desktop background does nothing. In the task manager (the bar at the bottom of the screen) and in the Dolphin file manager app, however, ctrl-left does emulate the right mouse button correctly. So perhaps the problem is specific to the desktop (KDE Plasma in this case)?