Web Request Activity with Credentials

I've been trying to get a Web Request activity to work and am currently getting a log in page instead of an XML file that I am requesting. 

 

 

I've tried putting in credentials using both a CredentialCache.DefaultCredentials and a NetworkCredential with Username and Password. Neither has seemed to work for me and there doesn't seem to be any documentation on how to properly do this.

 

 

I've seen references to a question on the forum, however; the link doesn't seem to work anymore.

 

 

https://support.geocortex.com/essentialsGSCForum?sub-nav=forum&main-nav=essentials&#!/feedtype=SINGLE_QUESTION_DETAIL&id=906600000000Bn0AAE

 

 

I'm not sure if this is a problem with my Credentials or if this is a problem with the server I'm requesting the data from, but I would like to be able to cross out the web request as the source of the problem.

 

 

Thanks