If like us we chase updates and are now on 5.3 but this hasn't been released, so its built from github source.
In order to use marketplace plugins with a custom build, the easiest is to create a Plugins folder in your custom project. If it is not a C++ project you can convert it to one easily.
If you want to keep your project as blueprint only but recompile a plugin. Simply create a new project with your customer version of Unreal. Follow the steps in the video and then copy the plugin into your Blueprints Only project into the Plugins folder as showing in the video.
https://www.unrealengine.com/marketpl...