To get text message notifications, you need to make sure you've supplied your phone number and have SMS notifications turned on in your settings. Here's how:
To add your phone number to your account, go to your Dashboard and click on the Pencil icon below your name.
There, you'll find an option to enter your Phone number. When you've entered your phone, hit Save.
Next, navigate to the pop up menu and click on Settings.
Make sure the corresponding boxes are checked under Push Notifications, Email Notifications and SMS notifications.