Installing the Web-app
The DrumScroll web-app can be used without installation, directly in your browser, by visiting the app's page. In fact that is recommended way to run the app from a laptop/desktop computer.
However, for smaller hand-held devices like smartphones, the browser's address and button bar would often take up too much screen space, leaving little space for drum score display. Therefore it would be more effective to run it as a Web-App. To do so, start DrumScroll in your mobile browser, then choose the "Add To Home Screen" command. (Read this Wikihow guide or this HowToGeek guide for more information.) Once an app icon has been added onto your Home Screen, close the DrumScroll page in your mobile browser, and restart the app installed onto your Home Screen by pressing that new icon.
The DrumScroll app install this way could be launch offline, without an internet connection. It will also have its own local storage space for saving your drum scores, independent of the browser.