The most straightforward and legal way to get "Dead or Alive Xtreme 3" on PC is through Steam. The game is available under the title "Dead or Alive Xtreme 3: Scarlet" on Steam. You can purchase it there.
Playing DOAX3: Scarlet via a Switch emulator is currently the most stable way to see the game running on a PC, often allowing for higher resolutions than the original hardware. Why You Should Avoid "Free Download" Sites dead or alive xtreme 3 pc download free