They mean signing into Active Directory, not the server (the server too, I'm sure.) Do your users have MFA when signing into their desktops?
No they don't have MFA for signing into the desktops.
They also mentioned MFA for routers. Not sure the edgerouter can do this.
They LIKELY mean for a VPN on the router, not for the login. But for login, you can do MFA if you only log in via SSH with certs.