Called when a non local player connects to allow the Lua system to check the password.
The default behaviour in the base gamemodes emulates what would normally happen. If sv_password is set and its value matches the password passed in by the client - then they are allowed to join. If it isn't set it lets them in too.
A user access whitelist to the server.
Available pre-defined messages can be found in
../sourceengine/resource/gameui_english.txt files or here.
Suggested messages are