At this point you should have feedback form with integrated
<Form /> component in your docs.
Go to Dashboard (opens in a new tab) page. Choose project where you want to see Feedback form submissions. Then click on Submissions tab inside project's view.
Then you will see table of submissions that customer left. You can click View in table row you will be able to see submission details
That's all, you should be able to collect written feedback from your customers.