Fresh installation, Lazyest Gallery menu does not appear

I am trying to setup the Lazyest Gallery, but I cannot get the Lazyest Gallery menu to appear. I have specified the gallery upload folder (wp-content/uploads/lg-gallery) with proper permissions set and the page I want the gallery to appear on, with the [lg_gallery] code inserted.

Also, at the bottom of the settings page, I see the following error:
Fatal error: Call to undefined function get_users() in /var/www/tucsonpack747.com/wordpress/wp-content/plugins/lazyest-gallery/inc/functions.php on line 340

Not sure if those are related.