The web part is intended for split use between documents and projects, some custom search managed properties are referenced that need to be changed, but the web part can be used as is for simple documents search.
Some of the helper functions are blatantly stolen from Elio Struyf's SearchVisializer: https://github.com/estruyf/react-handlebars-search
The difference here is that this web part uses sp-pnp-js for all the queries to the search api, and datatables.net to display the results.