Apple does not allow apps to be installed from a website, so on iPhone and iPad the site is added to your Home Screen instead. It opens like an app.
Leaving this page will stop the install from starting.
The app has not finished being prepared. If you leave now, you will need to start again.
Install turns the whole website into a real app, with every paper, image and video inside it, so it works without internet. The app is installed on your device like any other app. Because every video is inside, the app is large (over 1 GB), so use a good connection to download it.
Checking what is available for this device…
Get the app for another device. Open the file on that device to install it.