For customer input question data to show inside Mailchimp, it's not enough to define the Variable ID inside Lantern ( that's only for internal analytics purposes). The variable ID must correctly be defined inside the Integration options so that Klaviyo and Mailchimp recognize the value entered as being a customer's first name.
For Mailchimp , the property for first names already exists inside their system and for it to be recognized when data is sent over, the variable name must be FNAME.
Names are just an example of customer input questions. You may want to ask people about their eye color and create the variable eye_color inside our app. For the data to be passed to Mailchimp, it's important that you create a merge tag for eye color inside Mailchimp as well.
You could give the merge tag the same name eye_color inside Mailchimp. After creating it you must come back inside the Lantern Quiz Builder and add the eye_color merge tag as the Mailchimp ID under the Integration options so that Mailchimp then knows when it receives this information where to send it and what it means.
This article will help you better understand how to create and set up a new merge tag inside Mailchimp.