The Media A to Z plugin adds three new taxonomies to the media library and two new page templates.
Media taxonomies: A to Z, category and document type.
Templates: Document finder, Media A to Z
The document finder was updated in version 4.28. The original page template was removed from the theme and transferred to the Media A to Z plugin. You no longer need the Media Categories plugin, and you should deactivate this plugin.
You must install and activate the HT Media A to Z plugin to enable the taxonomies and templates.