JSFiddle - React, Tailwind, and code Playground

HTML

<span id="count_tovar"><script type="text/javascript" src="https://accounts.e-autopay.com/external/widgets/pincodes/246928"></script></span>

<input type="number" min="0" name="count" id="count" required="required" />

JavaScript

let el = document.getElementById("count_tovar").innerHTML.toString().replace(/<[^>]+>/g,'');

console.log(el)

let input = document.getElementById("count");
input.onmousedown = input.max = el;