[wpdm_tree] shortcode doesn’t work

I have installed the latest version of your plugin, but when I add the [wpdm_tree] shortcode to a page it doesn’t work and just displays as [wpdm_tree] on the frontend. I confirmed that your plugin description page claims that one of the features is

Complete category and file tree using a simple short-code [wpdm_tree]

I also see mention of it in the readme.txt file within the plugin but I see no reference to “wpdm_tree” within an add_shortcode() method in the code of the plugin.