Reference: https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-configure-RADIUS-authentication-for-switch-management-access-in-EXOS/?q=exos+radius&l=en_US&fs=Search&pn=1

• Configure radius server ipaddress as primary server and the switch’s ipaddress as the client-ip.  Be sure to specify the correct virtual router
  • configure radius mgmt-access primary server <server IP> <server udp port> client IP <client IP> vr <VR>
• Configure the RADIUS shared-secret
  • configure radius mgmt-access primary shared-secret <shared secret>
• Enable RADIUS for management access
  • enable radius mgmt-access

On the RADIUS server a normal user is needed for user access. If the user needs admin privileges on the switch the RADIUS user should be configured to send the RADIUS Service-Type attribute with a value of  Administrative. For further information on this attribute, see Section 5.6 of RFC 2865.

Additional Notes: The RADIUS server must also be configured to accept and respond to access requests from this device.
How to configure radius server to provide admin level access / privileges to users