Troubleshoot Zoho Campaigns Setup & Integration With WooCommerce

Current situation:
Customers are asked at checkout whether they would like to sign up for offers using the Zoho campaigns plugin for WooCommerce. This works OK and the details are passed correctly HOWEVER the issue is that unless the customer is already signed in, they are marked as 'marketing not allowed' which means it is not capturing their opt in status correctly. Even if the customer checks the box, they are not sent the auto follow up emails as desired.

Potential resolution:
We would like to explore how we can make this work, either by hard coding a separate sign up form into the checkout page, or adjusting things to make it work. I am open to suggestions.

Please do get in touch if you need more clarification.
Experience with Zoho or Zoho campaigns is required.

Budget is somewhat flexible depending on scope of project.

Site URL: https://joshuab267.sg-host.com/checkout/