The DLCs I purchased cannot be installed on MacOS

I purchased three Sims 3 DLCs (Seasons, Supernatural, and Generations) via Steam as the Spring Sale is currently on. Knowing that years before, I had purchased the Sims 3 + Pets on Steam and had no trouble using the provided CD keys to prove my ownership of the content on EA App (previously Origin).

I redeemed the CD keys for each of the DLCs with no issue, however when I try to install these DLCs on my MacBook, it says that they're only available on Windows. Furthermore, when I look at the Sims 3 DLC store within EA App, it says that Seasons, Supernatural, and Generations are all still available for purchase. This is strange because in that same store it says I own the Pets DLC and I cannot purchase it again.

I should mention that the reason I can only play the game via EA App is because the MacOS version of Sims 3 isn't available on Steam. This should not be an issue, though, as I purchased the base game + Pets via Steam and can access that content with no issue.

TLDR: Bought 3 DLCs on Steam, redeemed the CD keys that came with them without issue via the EA App, and now cannot install the extra content as it's supposedly only available on Windows.