If you are running macOS 10.14 Mojave and getting the CAS errors, try this:
Right click the World of Warcraft.app and select Show Package Contents.
Go into Contents>MacOS
Right click on the World of Warcraft Unix executable and select Create Alias.
Move that alias out to the game directory and double-click that.
Now the down side is that the Terminal window stays open the whole time in the background, but at least you're playing.