Create a gravity form with the required mapping fields and select form type invoice/quote from the Invoicing tab and use shortcode to display form.
Create WPI Gravity Form Feeds from the gravity form form settings->WPI Gravity Form. Select type for invoice or quote and map the form fields with invoicing fields. Email is the required field for creating invoice/quote.
When user request quote or invoice from gravity form, admin can add items to the quote or invoice later and send it to the user for payments.
If the email address submitted in the form is not already linked to any customers/users then this add on will automatically create a new customer with this email.
Once you have above plugins installed and activated, you need to create form with following fields and map them in the gravity form feed page.
* Customer Email
You can also use the following optional fields for getting more data for invoice or quote:
* Customer Name
* Customer First Name
* Customer Last Name
* Business Name
* Zip Code
* Phone Number