This integration works only for referral programs with goal-based rewards and referral contests, as only in these types of referral campaigns you have an access to participants contact data. This integration allows you to pass participants emails to MailChimp and keep them synchronized for further email marketing purposes.
To activate MailChimp integration first of all you need to go to the participants page when your campaign is set up. You could do this by clicking on the following icon:
Then go to the bottom of this page where you find available export options and choose MailChimp from the list:
After it you will be asked to log into your MailChimp account.
After you enter your account details and press on "Log In" button you should see all your MailChimp lists, it should look like this:
If you'd like to have a special list for your brand promoters you could do this from your MailChimp account and then just press "refresh" button to see it. If you decide to cancel synchronization then you need to choose "Disable synchronization" option (see picture above).