There is no Auto save feature in Photoshop. There is an Auto Recovery feature you can that cane recover some editing done in current open Document if Photoshop crashes, You system crashes or you lose power. If you close documents without saving the they are gone. There are no files for them.
There is an auto-backup feature availaible on the Mac. It is called Time Machine and you can Google the setup, the features and method for retrieving information. If you put Time Machine in the Dock and right click, you will have the opprtunity to see its Preferences. Here is part of the display:
As far as I know, that only works, as mentioned previously, when your computer crashes. It also works if you're working on a cloud document. Cloud docs will be saved automatically, when you close them, which could be a bad thing, if you didn't want to save what you had done, like flatten an image.