The plugin you are describing hasn’t been updated in nearly two years.
Here is a method to do what you want, in a better way. It lets you use ANY widget on posts in certain categories.
Manage an infinite number of sidebars. Make your WordPress site even
more dynamic and boost SEO by controlling what content the sidebars
should be displayed with. Creating flexible, dynamic sidebars has
never been easier, and no code is needed at all as everything is
easily done in the administration panel. No extra database tables or
table columns will be added.