Illegal? Like, the police will knock to your door for sharing a patreon project? What kind of cyber dystopia you live in?
Even legally talking, what case will it be? Stealing? Stealing what? You don't buy a product, you buy a subscription to get a reward, which is a game that's probably not even licensed in any way, since it's an indie without a publisher or anything.
The idea of getting to jail for that is crazy for me. If it actually worked that way, this website probably wouldn't exist, since it's quite literally a place for getting paid porn games for free.