The rules of Itch are clear, if you have "Collected by itch.io" in addition to complying with the itch rules, you must comply with the rules of paypal and stripe, if you do not, your game may be removed from the "Collected by itch" system .io" and you can only use the "direct to you" one.
If your game does not receive any type of economic benefit, then you must only comply with the Itch rules.
https://itch.io/docs/creators/faq#is-adult-content-allowed
If you plan to collect money for your content, then you must adhere to the acceptable use policy of all respective payment processors that your account utilizes: