html "include"

I am attempting to “include” a form written in html onto a Tesseract Theme page. I have tried various ways of “including” this form to no avail.

I have tried it on a open page. I have tried it with Beaver Page Builder on a HTML module. nada

My last attempt was

<?php include(ABSPATH.”/wp-content/themes/TESSERACT/inc/calculator.html”);?>

Do I need to create a template to then call this form?

Any help?