Installing diablo 2

hello,
i downloaded the diablo 2 and expansion onto my windows 10, but when i go to install the game, it only allows me to enter in a 26 digit cd-key. i have an original copy of the game that has a 16 digit cd-key. what are my options?

You have to redeem the old 1s for the new 1s if ther not Claimed already if thay are you have to buy a new sets of 26 digit keys

thank you veovix i will check into that