How to Download All Photos from iCloud to Mac

1. Open the Photos app on Mac.
2. Select all photos by hitting Command+A, or by going to the Edit menu and choosing Select All.
3. With all photos selected, pull down the File menu and go to Export and choose Export Unmodified Originals.
4. Choose the location on the Mac to save the photos from iCloud Photos to.

You can download photos from iCloud to an external drive using this, just make sure the external disk drive is selected as the destination.