So, I figured it out, it's pretty simple. As it says in the guide, your forum account isn't the same as your Loginserver account. A DB error in this case is just wrong password for the account you're trying to log in with. My old Loginserver account name was different from my forum name.
Go here to change the password for your Loginserver account.
https://imgur.com/a/BIC5SQh
I got the sms sent to my phone, changed the Loginserver password and used the correct Loginserver account name, and was able to log in. I had a feeling it was something simple like that, but it's an honest confusion. Hopefully this helps.
[Edit] Basically, I was trying to log in to the game with my forum account, when I should have used the Loginserver account, derp.