To set up the custom checkout option in your ecommerce mouse over settings and click on custom checkout.
A single custom checkout field can be set up. You can choose for it to be a paragraph or a checkbox.
The label is the title of this section that your clients will see on your live site. "Special instructions" is a common label for paragraph.
To allow clients to see the custom checkout information, you need to choose yes under the visible option.
By setting the custom checkout to required, your client must either check the checkbox or enter in text to complete the checkout process.
Make sure to click save changes after you set up your custom checkout options.