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.