Wix Automations with Zapier - Missing Email Address Variable

Hi, I'm trying to connect purchase made in my Wix store, through Zapier, to create an account in a third-party system "Matrix" (part of Cypher Learning).

The aim is to use the email address the customer enters at the Wix checkout to create a new account for them in Matrix and enrol them in a course.

The problem I'm finding is that the data pulling across from my Wix Automation doesn't include the all-important email address (screenshot attached of the data fields it does bring).

Without the email address, the whole thing doesn't work. I've tried adding in a custom field to my Wix automation but that doesn't show up either; seems only the Customer First Name and Customer Last Name are the only user-entered fields that are included.

Is there way to fix this?

Thanks