Manually Install Plugin? Originally Didn't Copy Templates

Yep. Manually copy the template folder into your theme via FTP:

The plugin works by copying css and template files into your active theme on activation. If the KBE template is unavailable, it means it did not copy those files in correctly. Reasons for that might be a permission issue (your theme directory may not be writable), or perhaps you’ve changed themes, or some other reason.

Whatever the reason, you can easily solve the problem by manually copying the relevant files from the plugin, into your active theme folder. The files you want are in wp-content/plugins/wp-knowledgebase/template and you will need to title the folder /wp_knowledgebase