MailChimp Email triggered by Squarespace form

My goal is to use MailChimp to send an automated email reply when viewers enter their email address into a Squarespace form block. The list dropdown in the Squarespace forms does not contain the campaigns I have created in MailChimp. The accounts have been integrated together. 

Is there a different way I need to set up the campaign in MailChimp so that when I go into the Squarespace form storage list, the campaigns will appear? 

Thank you. 

Hello, did you ever find a solution to this? I'm trying to do the same thing. The goal is to trigger an automatic email response from Mailchimp every time a user submits the form on Squarespace.