The designer is an Editor Mode created as a plugin for Unreal Engine 4.
Plugins are always located in your plugin’s directory. In order for plugins to be found, they must be located in one of the valid search paths for plugins in Unreal Engine. Pasting the Designer folder inside the Engine plugins directory will expose this plugin to all your projects. Any time a new engine version is installed the plugin has to be moved to the new engine versions’ folder.
