I have been reading the Unity AR & VR by Tutorials first edition book and I have imported everything it has told me to and everything has been going well until I had to add the VRTK_SDK Manager component to the game object that it told me to make and name [VRTK_SDK_MANAGER]. When I click on add component nothing comes up with the name VRTK_SDK_MANAGER and even when I search up vrtk nothing pops up. If anyone knows why this is and could help I would appreciate it, thanks!