Hi there! I created a cpt for class registration. It has title, desc, date and time. When you click the register button I want Fluent forms to capture the title, date and time from the cpt in Meta Box and submit the form. The title, date and time are not actual form fields because this data is coming from Meta Box fields. So no matter which class I register for the form submit button needs to get data from the cpt fields. I'm assuming these fields are probably hidden. When I have some direction I will reach out to Fluent Forms support.
If you use the Fluent Forms to create a form on the frontend to submit posts, I think it works like the extension MB Frontend Submission. So you can follow the documentation to know how to use the custom field to re-order default fields (title, content, featured image ...) https://docs.metabox.io/extensions/mb-frontend-submission/#reorder-post-fields
Then you can use these fields with Fluent Forms as well.
And please note that these fields will be hidden when you edit the post because they have the same IDs as the default fields of WordPress.