Unlike the full version of Dead or Alive 6, the free version which has a title of Dead or Alive 6: Core Fighters just offers the basic features and limited characters. However, players will have the option to purchase a single character if they want to.
Looking at the game description, it seems that Bass, Diego, Kasumi, and Hitomi are the only characters available for free in Dead or Alive 6: Core Fighters. As mentioned above, players can buy other characters for $5.95 each. All in all, if you want to get all the characters, you need to spend around $90.95.
You can check the game trailer below: