FAQ - Age of Empires 2 Definitive Edition
How to Make Allies in Age of Empires 2
A. To be able to ally someone in Age of Empires 2, before starting the game, you should uncheck “Lock Teams”
Then ingame click the diplimacy button (Top right side)
a small window pop up that lets you become an ally or enemy to a human or an AI.
Go to how to send resources to learn the hidden secrets on how send resources without taxes and how to earn more gold.