YOU DO NOT NEED TO DOWNLOAD THE LEGACY EDITION IF YOUR MAC IS A 2012 MODEL OR LATER. You will need to run the Legacy Edition of the game. *If your Mac is a 2011 or earlier model it is not Metal compatible. Minimum OS -macOS El Capitan (10.11) Metal compatible*.However, these are the recommended requirements which are more relevant when you start adding in Expansion Packs, Stuff Packs and Game Packs:
First of all, make sure your Mac meets the minimum requirements: