As a part of Stripe's verification process, they do ask for your charity's website. As Donately works with hundreds of small nonprofits, we recognize that you may not have your own website. With that in mind, you can always use your Facebook page as your website. Just be sure that it's the URL of your page. Typically, this is something like "https://facebook.com/mycharity".
If you do not have a website or a Facebook page, please see this article for your options: https://support.stripe.com/questions/unable-to-complete-account-activation-without-business-website