Plugin Location

The plugin is installed via the Epic Games Launcher. It will be installed into the folder

/UnrealPath/Engine/Plugins/Marketplace/FtsTriggers

To install the plugin on a project level move the FtsTriggers folder to

/ProjectPath/Plugins/FtsTriggers

Enabling the Plugin

Go to Edit -> Plugins and search for "Triggers" and enable the plugin. The editor will prompt you to restart. After that the plugin will be enabled and available.