Configuration with Campaign Monitor

1. Add Campaign Monitor API Key from your MailChimp account. Here is link to get Campaign Monitor API key - https://help.campaignmonitor.com/topic.aspx?t=206

2. Select list for your account.

3. According to your Selected list, the merge fields will be displayed under 'WooCommerce checkout fields'.

4. You can add more custom fields.

Note: These merge fields come from MailChimp List. First you have to create custom fields in MailChimp for a particular list.