Creating a dynamic Drupal form?

Question

Drupal

Good evening, actually interested in the question.
I'm struggling with the implementation, the form is very similar to the example on the site.
Briefly about the example:
1. click "place an order"
2. The form for adding data pops up. (this data can filter the final set of required documents)
3. Click "continue"
4. We get to the page with documents where we already fill in the files we need.
What I got: I
got a multi-step form in a modal window ( Webform ) with dependent fields. But this is not quite the same, in the example it is clear to us that google dev tools makes it clear that there is only one form and it is with contact information. And the file page is just a dependent page.
Can you please tell me how to implement this functionality?
P.S. I understand that I will have to at least alter the form. But I just may not have enough experience to at least correctly write an action plan. And then I’ll make the form and I won’t move further =( Thank you very much in advance.

Answer 1

The task is not clear, try to write more clearly what you need to do, and by the way, has it already happened?