Edit in JSFiddle

const material = document.querySelector('a')
material.textContent = ndst.content.eutk2[3].title
material.href = `${ccloudserver}${ndst.content.eutk2[3].filename}`
<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>

  <a></a>

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

</body>