On EXOS switches, once logged in, you're in "enable" mode - it's like some cisco devices where your username is automatically in 'enable'
Looking at the message that comes back, that's coming from the TACACS server telling you "you're restricted". As Alexandr said, you'd need to set the appropriate command rights and/or levels for your user on the TACACS server's config.
As a last resort, turn off the tacacs server, and log in with the locally defined admin user on the switch At least on my switches, if tacacs isn't available, it falls back to local users - but ONLY if the tacacs server isn't available.
Frank