If this option is missing then it means that it's not enabled in the menu screen option. See related link with steps here.
To use the Maps JavaScript API you must have an API key. The API key is a unique identifier that is used to authenticate requests associated with your project for usage and billing purposes.Read more here
If you have FTP or CPanel access you can modify these files (.htaccess File, Functions.php File, php.ini, wp-config.php) or simply use the 'Plugin Method'. Not everyone is a fan of writing code or accessing root files using SSH or FTP. For that situation, the plugin comes in handy and luckily there ...