CRED plugin provides an API, making it easy to customize your post or user forms. The API includes hooks (actions and filters) to accomplish specific tasks using PHP code.
When you ask for help or report issues, make sure to tell us all related information about your form and what you want to achieve.
Problem: I would like to create a one-to-many relationship between Users and a post type.
Solution: You can either create a proxy post type for Users and relate that proxy post type using Toolset's Post Relationships feature, or you can create a custom usermeta field that stores a reference to the related post by ID.
Problem: I would like to provide visitors the ability to create both free and paid posts on the front-end of the site using Forms.
Solution: In the current software this requires two Forms - one for free posts and another for paid posts. A more custom solution that provides both options in a single form will require custom code.