The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Shafford Ryle Limited:
Use your iPhone or iPod touch to provide a label, title or banner for your photos. Either position your iPhone alongside the subject of your photograph, or take a photo of the iPhone screen before and/or after taking the shot.This helps supplement the date information provided on your camera, which can be helpful after a long day of shooting. I have found this very useful when taking pictures of flowers, and when making a catalogue of items for insurance purposes.The app includes title, subtitle, optional date and time, optional index counter and optional bar for correcting the colours of your images later.