Hi, I just bought a KastKing Sharky III 5000, my first spinning rod.  I loaded 150yds of braided line however, the line loaded with a heavy amount through the middle area of the reel and smaller amounts along the edges. I called KastKing Tech service, they told me it was human error but no reasons why and return it since it is still in warranty. What could I have done wrong?

What pound test line were you using?

Spinning reel line lay problem usually happen either the lip or bottom of spool easy fix with shim that come with reel. In the middle should mean you did something wrong or reel oscillation faulty. 
did you make sure to tight the spool to main shaft enough to not creat slipping when apply pressure to the line when spooling?

it seem like the spool doesn’t move up and down all the way while rotor turning. 
 

You are in good hand here, if you did everything right, contact Kastking for new working reel or refund, if no response from them, the mods here should be able to straighten it out for you since Kastking is heavy sponsor here.