Plugin files can be placed in one of two places to install them:

• Inside a project folder: C:/.../MyProject/Plugins/MyPlugin
• Inside Unreal Engine: C:/.../Unreal Engine/UE*.*/Engine/Plugins/Marketplace/MyPlugin

When installed to the engine, all projects on that engine version will have access to the plugin. If you want to load or modify a plugin in specific projects only, install a plugin files in the project folder instead.

I recommend installing a copy of plugins on the project level, so you have the most control over modifications and updates.

This can make your project's version control and backup systems easier to manage, and avoids data conflicts.

Installed plugins are listed in the project settings, and can be activated here. Ferrefy plugins have their own category.

Plugin specific instructions can be found in their documentation sections, if required. The project log can assist if a warning / error is logged.