To connect your Promolayer account to Mailchimp, complete the Mailchimp authentication process directly from the Promolayer dashboard.
Steps
Go to "Actions" in your display settings.
Under the Enter collected information into section, click the Connect to Mailchimp button under the Mailchimp heading.
A new authentication window will open. Log in with your Mailchimp account credentials.
Authorize Promolayer to access your Mailchimp account.
Once authorized, return to the Promolayer dashboard and select your Mailchimp audience list.