The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From Cumulus Computing:
View current Products and Quickly create orders for pick-up or delivery Receive coupons and specials instantly Reorder favorite items quick and easy Receive order status updates right up to delivery Store payment information for quick check-out