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 Ali Moeeny:
This is NOT an official NIH app. This app collects the time table of the scientific seminars and other events happening throughout the intramural program which is made publicly available by NIH (internally known as "the yellow sheet") and shows it in a mobile friendly format.Information on the map are provided by the app developer as a very simple guides to find major buildings and are subject to change at any time.It happens often to people working in the main campus to leave their office for a seminar and realize they haven't looked up the room number or other info about the seminar. Also many visitors find it not very easy to find their ways in the NIH campus and having an annotated map could help a lot. Landmarks on the map (pins) are located with very high precision. This app is an attempt to make this information available to iPhone and iPad users on NIH campus.