Avoid any site that asks you to complete a "survey," download a separate "installer" (.exe), or provide a phone number to unlock the file. These are common signs of malware or phishing.
The most reputable place to find legacy Age of Empires II mods and campaigns is Age of Kings Heaven (AOKH) . It is a long-standing community archive.
If you are playing the Age of Empires II: HD Edition or Definitive Edition , check the Steam Workshop or the in-game mod manager . Fans often port these classic campaigns to work with newer versions of the game. Safety & Legitimacy Report
Find your game installation directory (e.g., C:\Program Files\Microsoft Games\Age of Empires II\Campaigns ).
Here is the "report" on where to find it and how to stay safe:
Searching for a free download of typically points toward a specific campaign or module for the classic real-time strategy game Age of Empires II (likely the Age of Kings or The Conquerors editions).
This is a fan-made campaign created many years ago. Because it is older community content, it is generally available for free as it was never a commercial product.
Drop the downloaded campaign file into that folder.