The following still needs to be cleaned up but it works. Editing as I get the chance. This works to create a button that when clicked will send the user to a checkout page and send line_items and notes to the webhook. Legend as follows: "orderTag = note textarea; updatec=update input button; redirect-href= whatever your page is"

Shopify Custom Checkout for Zapier Webhook

<!--progress bar edited From: https://www.w3schools.com/howto/howto_js_progressbar.asp-->
<!--Thank you html & countDown function from: https://www.jotform.com/help/89-Create-a-Custom-Thank-you-page-with-Auto-redirect-->
<!--redirect page-->
<!--create a new page and add this to the script area-->
<div style="text-align: center;">
<h1>Thank you!</h1>
<p> </p>
<p>Your request has been received and our team is reviewing. Need another estimate? Click Upload RFQ or Build RFQ Request on the tab above!</p>
<span id="timer"> </span>
<div id="myProgress" style="width: 100%; background-color: #ddd;">
<div id="myBar" style="width: 1%; height: 30px; background-color: black;"></div>
</div>
</div>
<script type="text/javascript">
function move() {
  var elem = document.getElementById("myBar");   
  var width = 1;
  var id = setInterval(frame, 30);
  function frame() {
    if (width >= 100) {
      clearInterval(id);
    } else {
      width++; 
      elem.style.width = width + '%'; 
    }

  }
}


move();
</script>
<script>
function countDown(){
    var timer = document.getElementById("timer");
        timer.innerHTML = "This page will redirect to your account in a few seconds.";
 }
countDown();
// ]]></script>
<script>// <![CDATA[
$(document).ready(function () {
    
    window.setTimeout(function () {
$.ajax({
        url: '/cart/clear.js',                       
        type: "POST",
data: {note:''},
        dataType: 'json',
        success: function(html) {$.ajax({
                                   url: '/cart/update.js',                       
                                   type: "POST",
  				data: {note:" "},			  
            			dataType: 'json',
  success: function(){ setTimeout(redirect, 2000)}
  
});
function redirect(){
window.location.href = "https://titan-dod.com/account";}
                                                               
                                  }
       });
       
    }, 2000);	
});

<!--cart.liquid page-->
<!--past this script at the top of the page, dont forget to rename the element id's-->
<script>
function addComplete(){
setCartNote();
var timetoready = setTimeout(clickUpdate, 1000);   
}
  
function setCartNote(){
var a1 = "READY";
document.getElementById("orderTag").innerHTML ="" + a1 + "";
}

function clickUpdate(){
document.getElementById('updatec').click();     
}


$(document).ready(function() { 

var checker = document.getElementById("orderTag").innerHTML;

  if (checker == 'READY'){  
    redirect();
      
 
                                   
  }
  else{}

             
});

 function redirect(){
  
  window.location.href =  'https://titan-dod.com/pages/thanks-you';
  }  
</script>