The Flipcause payment pages are all encrypted with bank-level security. They have a green lock icon on each of them that when clicked, displays this certificate (this is standard on all payment processing pages across the web). You'll also notice that all Flipcause tool URLs begin with "https," also indicating the SSL Certificate. Since all of your transactions will occur through Flipcause, your organization's website is not required to have the SSL. However, it is up to you if you would like to purchase it for the added peace-of-mind of your supporters as they are navigating the website.
For more information about security, see here: https://www.flipcause.