The 'System' option shows all those settings which affect your system. While there are many options, they are not often used.
You will note that this screen shows 'log out'. All security around and access to this system is driven by the users' Google Account name. Access will not be granted to users without valid Google Accounts which have been assigned access to the system. The Google Account may be a @gmail.com address but may not be. You can create a Google Account using your 'work' email which does not create a gmail address.