Hi,
are you hosting your form on external website, or are you using Portal?
We are hosting our forms on external website and this worked for me. After copying the script to the external page, I have added another script to initiate download after submitting the form. It looks something like this:
<script>
var pdfUrl = "URL with the pdf file";
MsCrmMkt.MsCrmFormLoader.on('formSubmit', function (event) {
window.open(pdfUrl, '_blank');
});
</script>
You only need to add the URL link for the PDF file in the var section (it is marked in red).
This on my end triggers automatic download, no new window opens, the form shows "Success" message, and you don't need to use Redirect URL
Let me know if this also helps you
MaiElorym