Topic on Extension talk:ConfirmAccount

$wgGroupPermissions['sysop']['createaccount'] = false; --> $wgGroupPermissions['*']['createaccount'] = false;

I don’t know what was the exact meaning of this and/or if the extension page was modified since, but it is written "Sysops can still create accounts directly. To disable this, add to LocalSettings.php: $wgGroupPermissions['sysop']['createaccount'] = false;" and it is correct: the extension disables the account creation (to replace it by an account request) and sysops can also create accounts.