Here is a guide to get downloads to work on a mac.

When you download the files, it will zip to the desktop.

MESH files will be a dark grey rectangle so all you have to do is open the drive your game is in then go to the House Icon with your user name, then open Document, then EA Games folder, then Sims 2 folder, then downloads.  Then drag all Mesh files in to this folder. May have to make this Download folder.

White documents with a folded edge, do the same way as meshes.

Sometimes you will download a set of downloads in one Blue folder, open and drag white document icons and grey mesh files the same way as above.... I don't think it works if you drag the entire blue folder.

Your not done yet, because after you are done, go through this download folder and shorten all file 13 characters  not including the .package at the end. for example  1111111111111.package. (The files look very greek, and has a bunch of numbers and letters, and is not named the way you have downloaded it at this point. Just delete some characters.)

It may take 2 times loading up the game for them all to show up.