I'm sorry that happened! The DLCs for PC and Mac are exactly the same. You can download the free Mac version of the main game from here and just put the DLCs you got from Steam into the Mac Our Life "game" folder . You don't have to buy them again to do that. But if you want the DLCs officially unlocked in your Itch library, you would have to buy them. Steam purchase can't give you Itch keys.