Quarks.gui empty

Hi all.
I used Supercollider on a Windows system. I worked with the Quarks Gui without problem.
Now I switched to the Mac. When running Quarks.gui, I get the Gui window, but it stays empty!
I’m probably doing something wrong. But I do not know what.
I get this message:

The usually issue here is that SC cannot find a Git installation on your PC. You must have it installed and SC must know where it (on windows a where git in a Command prompt window must return you the path where git is installed).

The doc is absolutely not clear on this.

Also make sure you have XCode Command Line Tools installed.