Firstly, locate your own PlayerController, inside your playercontroller go to Class Defaults (this is at the top center of the blueprint window, by default). In there look for PlayerCameraManagerClass, replace that with the BP_SmoothCamaraManager.
Now locate your PlayerPawn or PlayerCharacter, inside that one on the left top click “Add Component” and add the BP_SmoothCameraComponent.
This is everything you need to do in order to setup the kit. You can now use the kit and it’s functionalities!