Additional Settings addEventListener Doesn’t Work

In the long run I am trying to POST to a website when the form is submitted.
In the mid, I can’t figure out how to add a field into either form of the code (firstname, etc.) in my example below.
In the short, I can’t get anything inside of document.addeventListener to execute. I am testing it with this simple code below and it does not go forward to the URL I am calling. The initial on_submit alert does work, but the alert inside does not.

on_submit: "alert('beforehand');"
document.addEventListener( 'wpcf7mailsent', function( event ) {
alert('this works at least');
    location = 'https://amphealthalliance.com/';
}, false );

The form lives here: https://amplifire.com/free-trial/