Getting Error while running the project in the FaceTrakingMeshToggle

[dhirajthinksys]

Hi Dilmer Valecillos,
I'm a beginner in the Unity AR form the background of UI/UX. I saw your youtube video and learning the Unity AR.
I have downloaded the code from https://github.com/dilmerv/UnityARFoundationEssentials and trying to run the project in Unity but not a success.
Error (Assets\Scripts\ReferencePointManager.cs(8,26): error CS0246: The type or namespace name 'ARReferencePointManager' could not be found (are you missing a using directive or an assembly reference?))
I have added the screenshot for the error's Please help or advice.
Thanks