Need a Co-author widget

The only plugin I can find that will do this is outdated so any help would be great. Is there a plugin that will display the author’s of a post on the sidebar if there is more than one and if not than just the one author?

I want to eventually stop displaying author’s under the title of posts and move that info to the sidebar.

https://www.internationalpolicydigest.org/2015/09/18/prospects-for-a-more-peaceful-africa-the-potential-of-a-monetary-union/