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 Ignacio Z.:
This application provides you with offline maps for the city of Mexico that will help you in case of an emergency. In a very usable way you can find emergency points with just a couple of taps making it very fast and useful to find an emergency place. With this application you can see hospitals, police stations, pharmacies, embassies and more for any city in the world. Even if you don't have an internet connection wherever you are, or are traveling to, you can use the application as all the maps are saved for offline usage. Offline routing is provided in order for you to find the fastest way to get to any emergency point from any other point. This is the first emergency application with this feature totally offline!! Additionally new emergency places can be added and shared thanks to the usage of Openstreetmap. This also means new places are added everywhere all the time giving you the possibility to have fresh maps and also modify them before any emergency happens!