They mentioned that you'll be able to unlock them in game with their 'Likes' currency, no mention on when but I'm guessing whenever the steam version goes live. Patreons are also going to get their pledge amount converted to 'Likes' so they can buy the outfits. They also mentioned that there is no way to acquire 'Likes' other than playing the game (can't spend money after release). But who knows, maybe that will change.
I guess with the "Steam" version they mean the Campaign version and the Harem version is probably the "Patreon" version.
I guess with the "Steam" version they mean the Campaign version and the Harem version is probably the "Patreon" version.