Download this autoexec.cfg config and put it in:
Then open this config with nopetad or any other text editor that you use and replace 'your password here' with the password you got.
My password - 123456789
setinfo "NiDEAdminSecure" "123456789"
Or if you have already used autoexec.cfg with your settings, then just add to the end of the file follow line:
setinfo "NiDEAdminSecure" "your password here"
and replace 'your password here' with the password you got.
Restart your game after autoexec.cfg done, join the server & enjoy.