Creating an account on the Sense app is the exciting (and crucial!) start to your Sense journey. You can only use the Sense app with a Sense monitor, and vice versa.
Download the Sense mobile app by following this link on your phone or by searching for "Sense Home Energy Monitor" on Apple's App store or the Google Play Store.
Note: The mobile app is needed for installation. You cannot install your Sense monitor with the web app.