I registered onto warmane website but I cannot login to the game client. I downloaded from this : https://www.warmane.com/download and got it complete (17.9 GB). I chose the Wrath Of The Lich King - Windows client, because I want to play on Lordaeron server.
When trying to login the account name I use is the one of the website (LeKrach), also tried with the forum one, not working either.
I activated the account clicking on the activation link received on my mail address, i believe i did everything right.
Finally, I checked the realmlist.wtf file and it's written : set realmlist logon.warmane.ru, just like a friend of mine who's playing and logs in OK.
Might precise that I also have the original Wow client (from Blizzard) installed on the very same computer.