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 Instant Interactive:
Create math worksheets containing 10 problems that can be printed or sent via email.--- FEATURES --- Numerous settings to configure what problems will be included. Problems can be any of the basic math facts in addition, subtraction, multiplication and division.- Set the layout of how problems are presented.- Choose what part of problems will serve as the answer.- Currently, generated pages will be 8.5 x 11 inches in size (US Letter).- Purchase the full version to create worksheets with up to 100 problems and to optionally include answer keys.