, add a custom field to a wordpress export plugin

I need to amend an export and add a custom field to a wordpress export plugin.

We are using a woocommerce export plugin and need to add the 'add a message' field on this page to the export.
https://www.flowersbyflourish.com/product/long-stemmed-roses-yellow/

Can add a custom field to the export easily using the export plugin dashboard, but I don't know how to find the name of the field in the database. (See attached screen grab)

This is a 5 min job