What are the short-cuts to click buttons on a MacOS message box?
Actually, you can achieve the same behaviour in macOS!

First, you need to do as follows:


Go to Apple > System Preferences > Keyboard
Select the Shortcuts tab
Tick the All Controls radio button (see below)





Now exit System Preferences


Once you've done this, you can use the Tab key to navigate the various options (incl. buttons) in Dialog boxes. In the screenshot below I've selected the Don't Save button.



Once selected, just press the space bar as you would in Windows!