Unity no longer comes with the standards assets preloaded. However is still possible to get these assets to follow along! All you got to do is go to asset store and type in the search bar "Standard assets"select the one by unity technologies and import them. Now one thing to note is that when you add the FPS controller to the scene you will get 2 errors about the GUITexture being obsolete. These ones can be fixed easily by double clicking the errors in the console, this will open the codes in your IDE so you can make the following changes:
1 . To fix the error in ForcedReset.cs all you've got to do is comment out line 6 (by adding "//" at the beginning of the line) This line was just there to force the gameobject to add a GUI Texture component which is no longer supported by Unity.
2. To fix the error in SimpleActivatorMenu.cs right under line 2 where it says "using UnityEngine;" add "using UnityEngine.UI". Then in line 13 where it says "public GUIText camSwitchButton;" replace it with: "public Text camSwitchButton;"
With these changes I was able to follow along the tutorial using Unity 2019.3.0f1