Nostalrius Begins - Quality wow vanilla realm (1.12)

Hello,
This is my 7th day I'm trying to login and still it says incorrect password or username. Username is trouble9966, password isn't long, it's just 8 letters. I also followed that Nostalrius guide, downloaded game from site and it is 1.12.1 version. I really don't know what's the problem and if someone could help me that would be awesome.
Thanks.

Hey trouble9966,

That error means that the account does not exist. I would create a new account here https://en.nostalrius.org/#iwannaplay and try again.

Thanks a lot !