Yes, the 21 extra stories are paid DLC.
Unlike a lot of AVN devs, We decided not to go the typical route and lock the main game behind a paywall once the main story is finished. The base game has 21 Core characters and 7 Secret characters. We decided to keep the base game free forever, and the supporters kept asking for more characters (mainly goblins), so we decided to offer those as paid extra romance routes to add to your playthrough.
That being said, we're pretty fond of giveaways, 'cause we don't wanna just lock out people who can't or won't support an AVN financially. We've done quite a few giveaways. In fact, there's one active right now. The Fantasies Collection Add-on, which is the H-gallery addition to the game, is normally $10. But if you go to the link below, you'll see we're giving it away for free until the 24th:
https://itch.io/s/153331/wca-4th-anniversary-giveaway
So yeah. DLC means paid extra romance routes, typically not very closely tied to the main game's story like the Core characters and some of the Secret characters are. But that doesn't automatically mean nobody can ever get them for free, 'cause we like our giveaways.
Hope that helped clarify things :)

