Add it to your steam library, and it'll stay there regardless of platform. This title may even work with proton (steam play) if it isn't a Mac native title. But you can find all of this information on the store page.
Giving this away because I don't want it: Throne of Lies® The Online Game of Deceit HD57H-46DND-CG0GT Another one, Dream Daddy: A Dad Dating Simulator E5Z6Y-ZFTQW-766GM Endless Space - Collection PQ33K-787VJ-N622Z The First Tree JAJ0I-VFC5P-BIHFT
https://elderscrolls.bethesda.net/en/tes25 Get The Elder Scrolls III: Morrowind through Sunday, March 31st. Log-in to Bethesda.net or create an account following the steps below to redeem a free copy for PC! 1) Create a free Bethesda.net account. If you already have an account, proceed to step two. 2) Log into your account and redeem the code TES25TH-MORROWIND to receive Morrowind on your Bethesda.net account. 3) The game will be applied directly to your Bethesda.net account. If you have not already, please download the launcher here.