Haha, thanks, mgebhard! I'm still really new to .net so a lot of this is still foreign to me.

mgebhard

Well, no.  The UserManager is an Identity API.  You'll need to install Identity into you project is you wish to use Identity.  From my perspective, you do not need Identity because you are authenticating with Windows atypically.  You still need to persist authentication.  Cookie auth does not care about the authentication source.  That's why you can use it without Identity as the link explains, 

Use Identity if you need to manage roles but you should uses Identity's external login feature if you go this route. 

Anyway, the official docs cover everything you need.

I've gone through the docs, and a lot of the the code in my post is from the docs, but it doesn't seem to work. Where in the docs do you recommend I can find the answers to my problem?

Or is there a way I can at least 'simulate' identity's UserManager? Like passing the user's name to the page with local storage or something better?