On top of creating blueprint accessible UTurret component, assigning everything as it should be, getting proper readings from HitLocation to get the Yaw, including my new Turret.h header only into .cpp files and properly setting everything in blueprint so the turret is on the right spot and is taken in as a UTurret in my c++ code, I also made FindDifferenceInRotation methods with different intake values to make my main code easier to read. After everything worked (with a little bit of a wrestle, but not much), I gave myself such a bit pat on the back that both my hand and back started hurting…
But the pain was actually so good 
Edit: Also I have noticed the weird behavior that Ben was talking about. When the turret is supposed to go over 90 degrees in Yaw it starts going all the way around again to get to that point from the other side. What a funny thing, that turret is.
Edit2: Also, I have noticed that every single AI tank is aiming at the wrong direction, but the closest. All the other AI tanks aim at the same angle that the closest tank is aiming, which means that they copy the Yaw on the turret of that tank, and Pitch on its turret, which is a weird bug. I wonder if we actually fix that in this tutorial.