Bluesky is a lot easier to use fresh out of the box. Even though their feature set is quite similar, Mastadon has a clunky and confusing UI, and still lacks a native iPad app-- instead they offer a poorly ported iPhone app.
That’s led to more people using Bluesky, and it snowballs from there.
Have you tried using Bottles? It’s a front-end for Wine that makes configuration easier: LINK