Wiki plugin crashes site when activated

I purchased the Wiki plugin. I unzipped and upload the wiki folder to wp-content/plugins.
On the Dashboard, in the Plugins menu, the Wiki plugin shows up appropriately. My website also loads appropriately in another window.

However, when I "activate" it, I get an HTTP Error 500 (Internal Server Error). The website also no longer loads (HTTP Error 500 (Internal Server Error) there as well).

I previously had Wiki Lite installed on this server, which was previously been deleted.

Thanks!