Worth mentioning is that im posting this for a friend, I walked him through the install. Nothing wrong there, I can log onto my main one without any problems.
I also tried making him an account and then logging into it from my PC, which didn't work either.
Don't forget, creating an account for the forums is not the same as creating an account to play the game. Go to https://en.nostalrius.org/#iwannaplay to create a game account.