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 AppDesign:
You want to know whether a particular year is a leap year? No problem - this app is your solution! LeapYear tells you whether the chosen year is a leap year or not. The App refers to the currently valid Gregorian calendar. In addition, the app gives you the necessary background and history to calculate the leap years.
