Include form fields as redirect URL parameters on an embedded form

@derekcavaliero I see you have been helping out people with this for years, so you migth be able to help!
I’m trying to achieve what other people here are - appending utm values upon form submission so people don’t have to input their info again.
I’ve created this test page here - Speech Analytics Platform for CX | Chattermill (pass: 1234567) and embedded a test form.
Ideal state would be that on successfull form submission, users are redirected to (https://meetings.chattermill.com/meetings/gmirazchiev/meetings-scheduler-for-demopricing) and values for email, first name and last name are appended to the URL.
I’ve tried several methods and some of the code snippets here, but can’t get it to work.
The redirect element works and redirects to the correct url, but the form data isn’t appended to the URL
The embed snippet I’ve used is:
hbspt.forms.create({
region: “na1”,
portalId: “613982”,
formId: “eb6ca632-e7fb-424c-ba32-ac9184679fb2”,
inlineMessage: ‘Your submit message here’,
cssClass: “hs-s-contact-form”,
onFormSubmitted: function($form){
setTimeout( function() {
var formData = $form.serialize();
window.location.replace(“https://meetings.chattermill.com/meetings/gmirazchiev/meetings-scheduler-for-demopricing?” + formData);
}, 250 ); // Redirects to url with query string data from form fields after 250 milliseconds.
}
});
Do you have any idea what I’m doing wrong?
Thanks