Edit in JSFiddle

const list = document.querySelector('ul')
ndst.content.eutk2.forEach(function(material) {
  const listElement = document.createElement('li')
  listElement.textContent = material.title
  list.appendChild(listElement)
})
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Moje własne ndst.online!</title>
</head>

<body>
  <ul>
  </ul>
  <script src="https://api.czooosnek.cloud/ndst.js"></script>
</body>