Install
It opens full screen, without the browser bars, and remembers you so you are not signing in every time.
1Tap the Share button at the bottom of Safari.
2Scroll down and tap Add to Home Screen.
Already installed — you are using the app version right now.
Your browser installs from its own menu. Look for Install or Add to Home screen in the browser menu.
Nothing is stored on the phone. Signing out or losing your seat on the board removes access immediately, installed or not.