Where is PlaceOnPlane component?

Hello,
I'm really struggling with the UNITY AR object interaction tutorial.

" select AR Session Origin object and add place on plane component" "then add cube prefab to its placed object property"

I can find the script for place on plane but not the component, so am stuck. I have imported both the tutorial and general ARFoundation assets. I can see the propoerty in teh script but can't make it run and provide the public bar.

Is there a better place to learn ARfoundation?

I am also getting a load of errors related to the assets (running unity 2019.4.2f1 and ARfoundation 4.0.2 - arkit and core also running at 4.0.2)
Thanks for any help