Hello Moshiur,
WPA2-PSK is a Layer2 encryption method, which is like a "shared key" you give to the
users you want to be able to access your WLAN. A database, whether local in the ZD, or
an AAA/RADIUS server, allows Layer3 username/password Authentication, or another layer
of security to your WLAN access. Please notice under Configure/WLAN, that you have both
Authentication Options, and Encryption Options. If you only need a shared passphrase to
all your trusted users, your Authentication would be Open, with WPA2-PSK Encryption.
If you want to make users login with a Username and Password, you can define them in
the ZD's local Database, if you create a Role with access to your WLAN, and Users with
the Role giving them that WLAN access. For this type of WLAN, you set your Authentication
Option to 802.1x EAP, with Local Database set as the Authentication Server. And again,
you can use one (simple) or the other (complex), or combine them both (must know PSK,
and have a valid uid/pw with Role in the local DB). Good luck and best regards!