How to create a delivery request form for my clients

I would recommend you to use a template, you will find multiple already created forms, clone one to your account and apply the needed changes. 

This request form templates category may help you: https://www.jotform.com/form-templates/category/request-form 

This guide will help you to use a template: https://www.jotform.com/help/106-How-to-Use-Form-Templates 

This chapter from our user guide will also help you creating your form: https://www.jotform.com/help/chapter-2-Create+Forms 

If you have any question, let us know.