Download Information:
For the game and expansion (not including patches), you will need to download two different files off of the internet. The first is the World of Warcraft Classic installer. This download comes directly off of the Mac Game Files website and is easily downloaded. Please note that it may take as many as five hours for the entire file to download, so I would recommend that you let your computer sit open and plugged into its charger overnight while it downloads.
Next, you need to download the expansion. I was able to find the direct download for this ironically right off of this website where it was listed as Windows. Please note that this file can take as long as ten hours to download, so again, I would suggest that you download this and the other file at the same time, starting the downloads a few hours before you go to bed and leaving your computer on to download during the night.
Downloads:
Mac_WoW_enUS_Installer.dmg
WoW-BurningCrusade-enUS-Full-Installer.zip
Installation Information:
The first file which is World of Warcraft Classic, comes in the form of a .dmg file, which means that it will contain an installer within the file similar to how a CD contains information. Open the file and then open the installer to begin installation. This shouldn't take too much time. I would also suggest that you keep the installer for World of Warcraft Classic on you computer so that you can install it on your computer just in case you want to play on a Pre-Burning Crusade private server.
The second file will come in the form of a folder. Inside the folder, you'll notice that there is both a Windows installer and a Mac Installer. Make sure that you open the Mac installer, which should be right at the the top in your window. Please note that in order to install the expansion, you must already have the prior file (listed one paragraph above) installed. Again, this should take very little time.
Patching:
Once you have the expansion installed, you must patch up to Patch 2.4.3. This is quite simple and only requires that you download and install each successive patch. Please do keep in mind that every time you finish installing a patch, your World of Warcraft will open up on its own and attempt to update your game to World of Warcraft: The Wrath of the Lich King. Simply quit out of this immediately and you will be perfectly fine. Below, the Patch downloads that are necessary are listed. You may also find these from Mac Game Files by searching World of Warcraft.
Downloads:
2.0.x to 2.3.0
2.3.0 to 2.3.2
2.3.2 to 2.3.3
2.3.3 to 2.4.0
2.4.0 to 2.4.1
2.4.1 to 2.4.2
2.4.2 to 2.4.3
Note: This guide wasn't written by me, and I do not take any credit for it other than slightly editing it.
