How do I pass on contact data to an unstyled HTML form on a landing page built and hosted on WordPress?

I am having issues with a form that is supposed to grab the contact’s email from the relevant query parameter in the URL, but the form is not working.

This is a little confusing, so let me start by explaining the steps the contact takes:

  1. The contact clicks on a LinkedIn ad and lands on a wordpress landing page.
  2. The contact fills out the Infusionsoft web form on the landing page. This includes email, phone number, as well as first and last names.
  3. When they submit the form on the landing page it redirects them to a thank you page.
  4. This thank you page has a form with 1 hidden field, the email, and a sign up button. When this form is submitted, a tag is applied.

The process is breaking down at step 4.

I ran a fake contact at step 2. This contact and all the information went through to Infusionsoft perfectly and the URL for the thank you page has all the URL parameters correctly set up: https://nowmediagroup.tv/free-audit-thank-you/?contactId=767683&inf_contact_key=883f74daba126b639411e32a58b3ed4267973ce9ce254bb676d421ab8f142ecb&inf_field_BrowserLanguage=en-US%2Cen%3Bq%3D0.9%2Ces%3Bq%3D0.8&inf_field_FirstName=Ernesto&inf_field_LastName=Valverde&inf_field_Email=ernestothebesto%40nowmediagroup.tv&inf_field_Phone1=123-456-7890&inf_J1ItP2IL3wpwpEvl=

However, when I subsequently click on the sign-up button on the thank you page (which is actually a form with a hidden field for the email), it doesn’t reflect in Infusionsoft that the form was submitted. It will reload the page (it’s set as its own thank you page, so the thank you page reloads the same thank you page), but it won’t reflect in the contact that the form was submitted.

If I understand correctly, since I am using an unstyled html form, rather than the javascript form, this hidden field feature will not work?

Is this correct?

And what would this javascript look like?