Once your App is ready, you can preview it on your smartphone or tablet by downloading a Preview App that is 100% white label.
To do so, click on App Preview from the left hand side menu of your dashboard:
and then click on the Promote button of your App from the App list:
and follow instructions to download the app.
Remember that if you don't have one already, you will be asked to open a Developers Account first.
Once you will have downloaded the White Label preview app on your smartphone or tablet, you will be asked to log in and insert the App ID, which you can find at the end of your App's URL.