If you are looking for an app to download photos from a profile you don't have access to, you should proceed with extreme caution. Here is why:
Consejos para una Descarga Segura y Ética descargar fotos privadas de facebook aplicacion
Legalidad: Dependiendo de la jurisdicción, descargar fotos privadas sin permiso puede tener implicaciones legales. If you are looking for an app to
Facebook Photos Album Download: For downloading your own photos or those you have access to: Checking the "Archive" or "Trash" folders
Mobile App: Go to Settings & Privacy > Your Information > Download Your Information.
Tap Accounts Center and find Your information and permissions. Select Download your information.