Origin issue - Sims 3 Pets download?

Hi

I recently uninstalled the Sims 3 with intent to reinstall it (and expansion packs) using digital download. The expansion packs I have are Late Night, Ambitions, World Adventures and Pets and all were bought on disc except for WA. I don't have the discs with me right now, so I used Origin to download them digitally (as I had them registered to my account). All is going fine, except Origin says that Pets is Windows playable only (I have a Macbook). I don't really understand this, since my other expansion packs are downloading (and installing) fine, and the disc I purchased for Pets is obviously compatible with Mac, as I've played Pets for years.

I'm just wondering why it's saying Windows only and how I can fix this, as I really want to install it. Also, if I ever lost the actual disc for Pets, Origin wouldn't let me install it digitally, which is obviously an issue.

Thanks for reading, please help me!