A free app for Android, by Dario Solera.
Dropbox is a service that hosts files and is frequently referred to as “cloud storage.” Although there are numerous rivals, such as Microsoft OneDrive, Box, Sync, and Google Drive, Dropbox is one of the oldest and most widely used cloud storage services available today.
You can download entire folders from your Dropbox account to your Android device with the Folder Downloader for Dropbox app: