Hi there. Yes, working frameworks is a bit confusing at the moment (I’ve been working to make it a bit simpler on iOS and tvOS, see here). To back up a second, if you just need SDL2 development libraries and headers on macOS, easiest way is via Homebrew, e.g. with brew install sdl2 sdl2_mixer <etc...>
If you absolutely need the libraries to be in framework form for whatever reason, I can walk you through some options (including building them from the Xcode projects included in the source repos.)