It’s actually quite functional, but the plugin installation is buggy. You need to copy a file from the plugin folder to the /wp-admin/ folder. Information is here, in this other thread:
https://www.ads-software.com/support/topic/406758
What it does:
Once properly installed, clicking on the “IImage Browser” toolbar button (from the HTML edit window) launches a new browser window from which you can navigate to different folders and select images for embedding in a post.
I learned about this from the Digging into WordPress book. The same content is here at https://digwp.com
HTH.