Microsoft owns AoE2 now. For a (often extended to 14 days), you can download Age of Empires II: Definitive Edition (which is 10GB+). After the trial, it is $9.99. This is not compressed, but it is the safest.
Assuming you have found what appears to be a clean .7z file of the 1999 version, here is the standard installation process. Microsoft owns AoE2 now
While the game is not strictly "free-to-play," there are several ways to access it at no additional cost or for a very low price: Microsoft owns AoE2 now