With our MailChimp integration, you can add your existing submission data to your newsletter list. To enable this feature, you should get an API Key and List ID from your MailChimp account.
To get a new API Key for MailChimp, please go to account link on navigation (avatar dropdown menu), and then go to Extras > API Key > Create A Key.
To get a List ID (Audience ID) please read this link: https://mailchimp.com/help/find-audience-id/
Please Note: Regarding the integration of MEC and MailChimp, you need to know that only the users who have done a reservation can be transferred to MailChimp campaigns.