So following along I came to the part where Sam added Tags under the Behavior tree only to find that I don’t have a GameplayTags under Project in Project Settings. Not sure how this happened, might be a new thing since I started in Unreal Engine 4.14.3, but after doing some reseach I found that if you want it in your project you have to manually open your DefaultEngine.ini file and add:
[GameplayTags]
ImportTagsFromConfig=true
Then follow the steps here: http://shootertutorial.com/2016/09/20/using-gameplaytags/
Then just restart you Unreal Engine by exiting and reopening project and you should be good. Hopefully this helps someone else!