These are the errors I get without the SteamVR plugin
Assets\SteamVR_Input\ActionSetClasses\SteamVR_Input_ActionSet_buggy.cs(17,59): error CS0234: The type or namespace name 'SteamVR_ActionSet' does not exist in the namespace 'Valve.VR' (are you missing an assembly reference?)
Assets\SteamVR_Input\ActionSetClasses\SteamVR_Input_ActionSet_srinput.cs(17,61): error CS0234: The type or namespace name 'SteamVR_ActionSet' does not exist in the namespace 'Valve.VR' (are you missing an assembly reference?)
Assets\SteamVR_Input\SteamVR_Input_Actions.cs(102,23): error CS0246: The type or namespace name 'SteamVR_Action_Skeleton' could not be found (are you missing a using directive or an assembly reference?)
Step 1: import Vive-SRWorks-Unity-Plugin.unitypackage
Step 2: restart Unity
Step 3: import Vive-SRWorks-Unity-Experience.unitypackage
Step 4: open scene Demo.Unity
Step 5: Play