Make sure that the Mailchimp addon is activated

Open Integrations -> Marketing and enable Mailchimp integration and enter your Mailchimp API key (where to find your API key?):

Now we need to create a process that will automatically add your new customers to your Mailchimp audience list.

  1. Create new process with
  2. Set event type to Customer Created
  3. Create Add contact to Mailchimp action
  4. Select the audience your want this contact to be added to
  5. Save it