AOD is a clan of narcissists that own a few servers that people play on and are usually the most populated servers.
Okay I am going to summarize what you have done so far, so people are up to speed when they jump in for the assist.
So you put the base game into a new folder( and I assume base game is updated because you got it on steam), downloaded the launcher again and let it install in the new folder and ran a integrity check.
http://blocked_domain/worjzy.png
Okay then, did you try this and hit the repair button?
*ignore the highlight*
You said you are missing a pk3, the game consists tons of pk3 files.
Do you know the specific one you are missing? Because if you try this and end up still missing the pk3 file you need, I can just give you mine and tell you where to put it so you can do it manually.
Also I forgot to say to take a screenshot of the error. The error you get when you try to connect to a server.