The App Builder has many privacy and design options.
App access restriction settings
a) How do users enter the App?
Use of a passphrase (set in the Passphrase field)
Use of email address and 6-digit verification code
Combination of both previous options
b) Who can enter the App?
Registered Attendees (For Event App only)
c) More privacy settings
Allows you more advanced App access restrictions.
2. App design settings
You can customize you App's icon, header logo, header color and landing page.