html:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="./scheduler-1.1.2-trial/build/scheduler.module.js"></script>
<link id="bryntum-theme" rel="stylesheet" type="text/css" href="./scheduler-1.1.2-trial/build/scheduler.dark.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>
<body>
<div id="app"></div>
<script type="module" src="./javascripts/main.js"></script>
</body>
</html>
import {Scheduler} from '../scheduler-1.1.2-trial/build/scheduler.module.js';
And I run my HTML on the ExpressJS server.