Hello,
If you don't set up payments on your account then no one will be able to send you any money for your project. You need to go through the payments setup in order to allow donations.
If you receive payments from us the you need to complete a tax form, even for donations. If you are a registered non-profit then you can use the tax documents we create at the end of the year in order to declare your tax deductions. (Note this is for United States, which I'm assuming you're in because you mentioned a w-9)
Thanks