Thank you for reporting this bug @Rjan and @JD1234. I had missed a hidden checkbox in the configuration of the form. I've fixed it now so you don't need a google account to pre-register.
@JD1234 I look forward to the day when we have reliable, easy to use distributed alternatives to tools like Google Forms. All of us on the IPFS project are working hard at building the protocols, data structures, and primitives that we need to make this possible.