Download on smartphone:
Launch the Dropbox App from the Home screen of your Phone
Tap the icon βββββ then βExportβ to camera roll OR tap on the photo you want to import and hold on the photo until the options bar appears.
Tap Save to Camera Roll.
Download on PC or Laptop: You could download single image or download all photos under Zip.file by Select All (click on Image, CTRL + A or Command + A)