To change your directory you have to locate it using the preference tab.File > Preferences > Sketchbook location: C:\Users\username\Documents\Arduino.
The above should be changed to Step_2_Addons.
For reference please use Lesson 1C.https://basecamp.robolink.com/cwists/preview/171x
If this does not work, please try deleting files located in: C:$Username\AppData\Local\Arduino15\staging
Then try checking if it works again.