You will need to host the HTML file somewhere that can serve HTML files in order to view it. This will currently not work to view the files directly from a local folder.
If stylesheets have not been included in the crawl, identify which ones are missing and add them in the Additional URLs field.
Documentation doesn’t really exist at this point. The next release of the plugin within the next few days will have better in-built documentation, so please try to update the plugin on the next release.
In the meantime, you may also like to try the Simply Static plugin here: