D2 Original 16 digit key. DL require 26 digits

Hello Blizzard CS. I bought D2(and LoD) Back in 2003. These editions have 16 digit keys in them; I managed to type in my LoD one some time ago but only recently found my D2 copy. I downloaded the installer and tried to use it; However the installer now requires a 26 digit code. How do I bypass this?

Thanks in advance

Check your games page in the account.
account.blizzard com/games#classic-game-accounts
There are D2 26 digit codes if you attached the game to your account. If not, you need to do it first to convert your cd-key then visit games page again.

There is nowhere to attach it anymore. That’s why I’m posting for help;