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 IBKR Analytics:
Chess Stop Watch app allows you to track the time of each chess players turn. This chess clock is sleek and simple in its design, and with only two screens to manage you can focus your time and energy on playing the game at hand. Personalize each game by entering chess players names for White or Black Set the time allotted for the chess game Play button takes you to second screen for countdown Option to flip one of the countdown clocks upside down so both players can easily see the time Simply touch the screen to send the move to the next player Digital chess clock shows Completed and Remaining time down to the seconds