In a rather unusual move, Google has released a screensaver utility for the Mac. The free app can be downloaded from the company's website and integrates within the screensaver settings under macOS.
Once installed, you will get all the best and most wonderful images from Google+ delivered to your Mac. There are no settings to configure here. You just enable it from your Mac's System Preferences and after the preset period your display will be showing the images, which switch every few minutes, always to something new.
You just need a version of macOS that is 10.9 or above and you're good to go.