I was able to get it to work in the Citrix Broker category. I added the username, password and domain there and left the NetScaler Gateway Authentication check box blank. 
In our environment we are currently using wnos.ini files to manage our Wyse thin clients and we're trying to get our ducks in a row for a switch over to WMS 1.3.  We have a group of Wyse ThinOS clients that are currently logging on with a preconfigured username and password via a mac.ini file.  I've moved one of these devices over to WMS but I can't seem to get the autologon feature to work. If I look at the WMS ini tab on the thin client the DefaultUsername= DefaultDomain= and Password= values are there and have the right info but the username, password and domain fields are blank. Am I missing a something or am I setting it up in the wrong place?  
Configure AutoLogon through WMS 1.3