Widget not showing

I was digging a bit through the plugin code to remove the time limit (easy ?? when I found code for a widget which shows the most voted comments. Now I activated widgets in my theme but the widget isn’t showing up in Appearance > Widgets.
Do I have to activate that somewhere first?

What I want to achieve is to make an overview of the most high rated comments.

https://www.ads-software.com/plugins/comment-popularity/