If you want a form where customers can fill in an enquiry, just activate it. Then you will create a page /inquiries where the inquiry form will be.
If there are multiple managers who can handle inquiries, assign a user and then for each inquiry you can select who will handle the inquiry.
Here you can prepare all possible demand states that you keep in the system. For example : Created, In progress, Finished
On the page that was automatically created for you is exactly this shortcode. If you want to have the form on a different page, just move the shortcode.