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 Columbia University Teachers College:
Congratulations Teachers College Graduates! Download the new Teachers College Convocation App to access important information for the 2015 Teachers College Convocation Masters and Doctoral Hooding Ceremonies. Graduates and their guests will have access to event details including: ceremony schedules, speaker information, and academic attire requirements. In addition to event details, graduates and guests will receive important announcements via the app including: registration information; dates and deadline reminders, and additional ticket distribution notifications.