I know it’s a charity bundle. I frequently support charity bundles, and understand how they work.
That doesn’t change the fact that I won’t, and many people can’t, use PayPal. The fact that PayPal will process a card payment doesn’t change that I have to sign up for a PayPal account in order for me to do that.
Edit: of the several charity bundles Ive bought, this is the only one that requires PayPal.
What he's referring to is that on Itch, there are two ways for "sellers" to get paid.
One is through Itch; the other is to pay them directly.
In this case, the bundle was set up by its creators as a direct payment option, and therefore, Itch can't do anything to change the payment settings. If you need other payment methods, you'll have to speak directly with the bundle creators.
EDIT:
By the way, you're on the general Itch forum, so it's best to try to contact the creators directly.
