Adding plugin through codebase

I downloaded the WebP/Avif plugin from the extensions marketplace through the NopCommerce site.

When I directly installed it, it could never find the Magick.NET DLL to properly work, despite my installing the plugin through the admin panel and activating it and even "Downloading the latest Magick.NET libraries."

My question is, how can I add this plugin through my codebase? It's not the source code of the plugin, so I guess it wouldn't go into the root Plugins/ folder.  I added it to the Plugins/ folder in Presentation/Nop.Web/ but it wouldn't show up on the Local Plugins list in the Admin Panel.  

Any help is appreciated.  Thank you.

That is the correct directory
Does the pluign version in the plugin.json file match the nopCommerce version?
Did you restart the webserver and /or Reload the list of plugins ?

If you mean this plugin
See https://www.nopcommerce.com/en/webp-and-avif-images-foxnetsoftcom
then contact the developer foxnetsoft