Are you using this with the 3rd person template? So you have all your input already created?
Have you followed Epics tutorial series on creating a 3rd person game? Your probably interested in 7 and beyond, just scroll to the bottom and select what you need to follow.
It walks you through everything you’d need to know. I am certain its something simple you have overlooked as it happens to me all the time. Can you link me the tutorial you followed and I can see maybe where you went wrong as its hard to tell since I can’t see your PC 
Cheers,
Alex