Users can now post in your site without registering themselves. You can enable guest posting by going to a form’s “Post Settings → Enable Guest Post“.
Auto user registration
Users can submit a post without registration, but you can auto-register themselves by enabling “Require Name and Email address“. That way, users will need to provide their Name and E-mail address. Upon providing their details, they will be auto registered in your site as a user. Their email address will be used to generate username, if a user already exists with the same username, a random number will be appended to their username. If a user already exists with the same e-mail address, the post will assign to that existing user.