To get ready to use interactions on your scene, all you need to do is to add next objects:
Game Tools
Can be located at \Easy Interaction System\Prefabs\Tools
Contains required scripts, to run Interaction System
Canvas Interaction Hint Controller
Located at \Easy Interaction System\Prefabs\UI\Canvases
Contains Hints Controller, and also there can be setted-up icons for interaction input hints. Hint controller are explained in more details on page Input hints
Canvas Inventory
Located at \Easy Interaction System\Prefabs\UI\Canvases
Contains simple inventory interface. Explained in more details on page Inventory System
Canvas Notifications
Located at \Easy Interaction System\Prefabs\UI\Canvases
Simple notification system. Explained in more details on page Notification System
That's all. Now, you can add interaction to your scene and use it.