You will encounter error 244 when logging into Guild Wars Reforged with an ArenaNet account that has Guild Wars 2 but no associated Guild Wars Reforged account.
You first need to create a new account using a different email from the one on your existing ArenaNet account by selecting "Create Account or Add Access Key" from the login screen.
After you create this new Guild Wars Reforged account, you can link it to your existing ArenaNet/Guild Wars 2 account, after which you can use your original ArenaNet login credentials. You will also gain access to Hall of Monuments rewards.
If this does not resolve your issue, please check the additional troubleshooting steps for the error in this article.