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 LI-COR:
Allows remote control of the LI-COR LI-6400XT Photosynthesis System. You can perform any action from your iPad that you can do from the XT's keypad. Uses WiFi for a local connection, and also supports internet access (via the LI6400.licor.com server) to any cooperating instrument worldwide.
