Can the user edit the form once completed?

You just need to create an auto-responder email, which will be sent to them upon submitting, then add "Edit Link" in that email.

I highly recommend that you read this guide for more information on how you can get this done.

You can also check the "Save and continue later" feature and see if it is what you need, here's a guide for it.

I hope I have been of any help.

Should you have any further inquiries, we will be more than happy to help.