As a designer, the first steps in the contest Handover stage are uploading the final design files, and signing the Design Transfer Agreement.
The customer will be notified that files have been uploaded to their Handover. They'll then sign the Design Transfer Agreement, and after downloading and checking the final design files they'll release the prize payment.
It's important to note that the Design Transfer Agreement once signed only transfers ownership over the design after the prize payment has been paid to the designer. Between signing the agreement and releasing the prize payment, the customer will still be able to request small tweaks to the final design if required.