The default individual entry archive template includes a block of template markup for posting comments… but that block doesn’t support Typekey authorization. You need to boost the markup from the comment preview template.

The text boxes on the edit entry page are tiny little things, because mt-static/styles.css is missing an entry for the full-width class. This can be fixed by putting this in your mt-static/user_styles.css:

.full-width { width: 100%; }