TinyMCE based on TinyCloud needs to register its website to TinyMCE. You can get a guide at https://www.tiny.cloud/docs/quick-start/

<!DOCTYPE html>
<html>
<head>
  <script src="https://cdn.tiny.cloud/1/no-api-key/tinymce/5/tinymce.min.js" referrerpolicy="origin"></script>
  <script>tinymce.init({ selector:'textarea' });</script>
</head>
<body>
  <textarea>Next, use our Get Started docs to setup Tiny!</textarea>
</body>
</html>