There are a few different ways new visitors of your app can be prompted to sign up and create an account. By far the easiest way to trigger a sign up is by toggling 'Require Login' on under 'Access' in your global app settings. When 'Require Login' is toggled on (& allow browsing is toggled off), new visitors of your app will be required to create an account and login to be able to access your content. For more information on configuring your access rules, (including paywalling your app) check out our access article.
With these settings on, the first thing a new visitor will see is a 'Continue with your email' popup: 
If they enter an email that isn't already associated with your app, they will hit a 'Create your account' popup where they can choose a Name and Password for their account:
Once they hit 'Create Account' the user will now be logged in to your app, and will be able to engage with any content they have access to.
Similarly, new visitors will also be required to create an account if they're trying to access any page that is set to 'Require Purchase' (even if 'Require Login' is toggled off), as product purchases need to be associated with an account.
Any page with its access rules set to 'Public' will be able to be browsed by anonymous visitors who don't have an account or aren't logged in. 'Public' access is the default access your app will be set to when you first create your account:
Users will only be required to sign up/login when they navigate to a page or piece of content that has its access rules set to 'Require Login', 'Require Purchase', or 'Private', or if they try to access account specific areas such as the 'Messages' or 'You' (account) page.
