Nostalrius Begins - Quality wow vanilla realm (1.12)

Hey, new vanilla player here. I just downloaded everything, registered an account, etc etc.

I've checked my email for anything needed, but nothing's happening.

I tried to log in with my username and password, but it ceases to work. It just says "The information you put in is not valid."

Yet, it works when I log into the site. Not the client.

Help?