@EpsilonAdmin Thanks for quick response and question.
Yes, my hope was to use the standard WP search widget - but I haven't explored any other option. If there's a better way I'm happy to get guidance

My site has been recently re-created in WordPress after quite a few years of running under Joomla and that Joomla installation had a free plugin called jiFiles (?) which did the document scanning/indexing. A standard search, scoped on file name or a string from within file content, would pull up a list of file names each hyperlinked to the file itself to easily click on for in-browser viewing (or possibly downloading).

I appreciate that there are other WordPress plugins that offer a full document management system but they have a much larger feature set than I need and are also majorly expensive for a small non-profit community web site.

@EpsilonAdmin I find myself also in this exact situation.
A small web site that is primarily about displaying a hierarchy of folders that contain mainly PDFs - using Simple File List Pro
I have only 3 top level pages. Everything else is generated auto-magically by SFLP when it scans the folders into which I have uploaded files manually (via CyberDuck)
using the eeFSL shortcode won't help if it simply results in one of those 3 pages being returned in search results.

Screenshot attached that hopefully gives an idea of what I have.

So, can WPFTS be enhanced to:
a) be pointed at a top level folder & told to index all files within that hierarchy; or
b) leverage the index that is created by SFLP

If getting this done would be helped by having access to my site feel free to let me know.