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 Chris McGehee:
Grade A+ tracks your assignments, classes, and GPA in an easy to use interface. Once entered, you have quick access to your list of upcoming assignments and can easily see which are due (or overdue) at a glance. WIth a single touch, you can mark the assignment complete and enter your score, Grade A+ will then calculate your overall class grade on the fly so you always know where you stand. No more guessing or asking the instructor what your class grade is - Grade A+ will do it for you!Grade A+ will also calculate your overall GPA and give you statistics for each assignment so you can see where you need to study more. Grade A+ is able to correctly calculate your GPA for semester, trimester or quarter based classes.