The plugin cannot be found on the Marketplace
It's not possible to find the plugin in the built-in plugin browser. The "Code::Stats" and "CodeStats" strings suggested on the codestats.net website's Plugins page don't find anything. I could only install the plugin using the direct JetBrains Marketplace website link from the Plugins page and clicking on the Get button there.
I have checked also the search on the Marketplace website and the string "Code::Stats" works there correctly (the Code::Stats plugin is the first result), but "CodeStats" returns only one result and that's incorrect (it's another plugin called "CodeStats").
I'm not sure you can influence any of those two search features (built-in and website), so would be good to correct the Plugins page on the codestats.net website.