You need to generate and copy a Maichimp API key ( how-to guide ).

1. Click on the Mailchimp tab
2. Enable Mailchimp
3. Paste your API key
4. Click on save so Skytake can fetch your lists
5. Select a list from the Lists dropdown.
6. Click on Save

Skytake will automatically add any new subscribers to your list.

How to add new subscribers to your mailchimp Workflow/Campaign (Premium)?

1. From your Mailchimp.com dashboard, click on the campaign section
2. Click Create Campaign
3. Search for "api", then click on API 3.0

4. Set a campaign name and select the right list, then click on Begin

5. Edit the trigger

6. Copy the campaign URL

7. Complete setting up your workflow and when your finish click on Start Sending
8. Now, you need to go back to your Wordpress dashbord Mailchimp tab
9. Enable Campaign
10. Paste your campaign url 
11. Click on Save