Prostream is accessible from all devices, whether yours is a desktop, tablet or mobile phone.
There is a mobile app for Prostream Quality. You can find it in the Google Play Store and the App Store and it works for both phones and tablets. In order to work offline and, for example, to perform quality checks, you need this mobile app.
There is no specific, separate app for Prostream Docs, because Prostream Docs works well from the browser of your phone or tablet. You could create an icon on the start screen of your device, so that you can open Prostream quickly.