In the "General Settings" session, enter the API Key code obtained from MailChimp, and then press "Save Changes" (don’t know how to create the API Key? Click here). After that step, a MailChimp list will be available to receive users registers from who register for the newsletter.
Once the MailChimp key is configured with a selected list, a newsletter widget will be available to be inserted on the systems pages that are allowed to be customized.
Information like the title, description and background image of the newsletter widget will also be available for customization.