Pass new members from external service through my signup form


I have a client who has the following scenario:

We have a marketing website in webflow, with a form where people from a third party service get free access to our service. The link they come with passes their first name and an access token, and then expects us to send back a payload with their first name, last name, email, password and that same token back.

Is this possible with Webflow Logic?

I have tried adding hidden fields in the signup form to pull in the url credentials with JS, but I have not been successful. Not sure it Logic just doesn’t recognize hidden fields, or I am doing something wrong.

Does anybody know, in theory, if this can be done, and point me in the right direction?

Here is my site Read-Only: LINK
(how to share your site Read-Only link)