Each Intervals account comes with its own custom subdomain. When logging into the Intervals mobile app, there is an extra step, as you have to identify the subdomain associated to your account.
When launching the app for the first time you will be given two options for logging in. If you know your Intervals domain name, press that button and enter your domain on the next page. You will then be redirected to your account login page, where you can enter your username and password.
If you don’t remember your domain name — or you’d rather skip entering your domain, username, and password — click the second button and a login link will be emailed to you. Click the login link in the email to automatically log in to your account via the mobile app.