Squarespace Payment form Integration with Mailchimp

Description

We use Squarespace to collect payments.
Here's an example of a product we have with a custom form: https://www.ppas.uk.com/book-a-trial/p/street-dance-intensive-course-ages-12-17
Upon purchase, we receive all the payment details in Squaresapce along with the custom form. We have connected the commerce api between Squarespace and Mailchimp and the data come across fine.
However we only receive name, email, billing address. We need the form details along with a tag created (the product name) attached to the contact. We would need the fields mapping also into the contacts with Mailchimp - for example we would like the Students name as the main contact name in Mailchimp rather than the billing name as the main contact.
We have tried tools like zapier but understand that it will require some additional coding / webhook integration that pulls our custom product form into Mailchimp.
Thank you for reading if you have got this far please put SPURS in your message so I know you have read through and got a solution that your sure would work.
All the best,Taylor