I got it working on my Samsung Note 4!
Follow the usual steps
-Settings/General/About/Click Build a bunch to enable developer options/Go back
-Click Developer Options/Turn them on
-Enable USB Debugging
-Click Revoke USB debugging authorizations (i think this does it, after you reconnect your phone via USB cable, you should get a pop-up with a box you need to check to authorize your computer - wasnt getting this before!)
Once you do that, you should be able to get the screen mirror process to work! assuming your phone is supported