Yes, you need some form of access control server to achieve this. You could either use the in-built Meraki Authentication, or if you're trying to align it with an existing user identity base (e.g. Microsoft Active Directory) then you need something to 'convert' to RADIUS - in the Microsoft Windows world this is NPS (although there are other better products out there too). Then you configure the SSID to use RADIUS authentication, so it sends the request to the RADIUS server (e.g. NPS), which in-turn checks against Microsoft AD.