automatically add discount code at check out with code_NARRATIVE THEME

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I manage the design and code for 4 seperate sites for 3 of them the following code on the cart-template.liquid code page will automatically add the discount code to the appropriate field on the discount code space on the check out page. however the the code doesn't work with the narrative theme. how do i make it work with the narrative theme. i really need it to work by tomorrow. please help thanks.
the code is:
<form action="cart" method="post" novalidate class="cart">
  <input class="js-form-discount" type="hidden" name="discount" value="BLACKFRIDAY2020" >