To use the app you need to put in the server URL and then the guest user count. The app requires a user and password login. If you log into mango with the guest user account and then click on the DGLux icon this will add the user into DGLux. You can then log back in as admin and go to the user edit section in DGLux and set a default mobile dashboard for the guest user. When the user logs in as guest the app will default to this dashboard. They will also be able to exit the dashboard and navigate the guest navigation file to open other dashboards.
I have no idea about opening the app from the browser, it's a good question and I've seen other pages work that way so I'm sure it's possible.