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 Waldman Media:
"ICE-Lock" helps you to create a Wallpaper for your Lock Screen with 1 or 2 ICE telephone numbers.In Case of Emergency (ICE) enables first responders, such as paramedics, firefighters, and police officers, as well as hospital personnel, to contact the family of the owner of a mobile phone to obtain important medical or support information.In iOS7 your phone is locked with a Passcode, which means that there is no way for the first responder to access your phonebook to find the ICE numbers you have added. If you create a Wallpaper with "ICE-Lock" the first responder just needs to view the Lock Screen to find your ICE numbers.