You would not be signing anything once you upload your game. Itch.io is a friendly and supportive community and is good place it upload to not only gather a fan base but also get feedback from other developers such as myself or general fans without being abused. I had look at the page and screenshots show a lot of the game and how it looks and will play. You done really well with including what the game is what will be included and it was a nice touch that you added how to made the game.