Now, If you ask him for permission, he may allow you to give advice to help players who are stuck at some parts. but I don't really know yet. After all, he is the one who made the game so you can ask him.
I will indeed only give vague hints, because the point of those games is to explore their worlds, think about them and connect the dots. If I gave away the answers, it would defeat my own work ;)
That being said, I'm fine with players helping each others if needed. Some of my games have pretty obscure lore or secrets that are meant to be discussed among the players. Though it's best if it happens outside of the itch's page to avoid spoiling newcomers before they even have a chance to try the games for themselves ;)