There are two possibilities for users to create and submit a feedback. First, there is the option to give a feedback to the current Project/Project Order/Order by answering to the default Feedback Questions.
At the bottom page of the Project/Project Order/Order details, click on the "Feedback" button:
You will be redirected to the create Feedback page.
When you click on the "save" button, you will be asked if you are sure to submit.
After submitting the feedback, its details will appear on the screen.
The other possibility is to create a feedback when an email with a feedback request is received. The link in the email will redirect the user to the create Feedback page shown above.