On the Zebo Platform this is the first tab in Build called Greeting
The Greeting text is NOT THE SAME as the Welcome Message (the Welcome Message is set in the Content tab). This is the screen that users see the first time they interact with your bot. Usually, if a user does not have a conversation active with your page, or has not messaged your bot or page previously, this is what they will see when they click on your ad.
Sample Get Started screen with Greeting Text