MySQL Whitelist creates a MySQL table in a database specified in the configuration file, which is then used to store the allowed Steam IDs that can join the server.
Configuration
The settings and options can be configured in the MySQLWhitelist file under the config directory. The use of an editor and validator is recommended to avoid formatting issues and syntax errors.
Updating the Whitelist
The plugin automatically updates all Steam IDs in the database each time the server saves, as well as kicking the players that are not whitelisted and that are currently on the server. There is no method to add users to this whitelist from the server.
Making a Database
If you're not sure how to make a database, I wouldn't suggest using this plugin as it's mainly used for servers that make use of this information elsewhere on websites and such.
Localization
The default messages are in the MySQLWhitelist file under the lang/en directory. To add support for another language, create a new language folder (e.g. de for German) if not already created, copy the default language file to the new folder and then customize the messages.