Hi.
if you look to the code you can see several #if UNITY_X_X
these are there to be compatible with other unity versions
when build, the versions that are not your unity version will not be added in your build.
Also when playing in editor, that code will not be used.
to place the object inside the activate game, you only have to click the 'use owner' and set to specify game object, then drag in the object.
OR
Drag and drop the gameobject into the action window, then select GameObject/GameObject/ActivateGameObject
Set property is using mirroring and is slow (as it has to go thru all code on a object)
also on mobile/consoles you will need to use Linker wizard else the code method parts used by propertied might not be included and break your game.