How do I unlock my device for KIES?
Try this

On your phone go to settings > developer options > USB configuration > and enable USB debugging 

To enable developer options, go to settings > about phone > and tap on the build number seven times.

(Make sure the phone is unplugged from the computer)

Plug the phone in, pull down the shade from the top, and select the USB options button.  Hit that, select software install.