Today, you have options. You can buy the for a few dollars and experience a superior version with multiplayer matchmaking. You can grab the DRM-free version from GoG. Or, if you are a purist, you can use the official UserPatch on your old CD.
The original 1999 version is largely superseded by modern digital releases that do not require physical media: Age of Empires II: Definitive Edition - Xbox age of empires ii the age of kings no cd crack