You do not need to pay for the base game, it is completely free, and donating is optional. Cutiesai also does not get to choose what payment options are available, that's entirely up to Itch. Please read the FAQ for more information.
It's very likely those DLCs weren't 18+, since they do not apply to Itch's current payment restrictions. The FAQ has more information on this. Also, just so there's no confusion, this comment section is primarily for the base game; any DLC comments should be left on the DLC's page instead.
