Apple exchange shipping with Fedex
I recently bought the new iPhone 8 and opted to send the old one by mail so I received my return box with FEDEX label on it. My question is who will be billed for this shipment and how do I send it back? Do I need to go call Fedex for pick-up and if so won't they charge me since I have to register online and do the pick up request? Thank you.
iPhone 7 Plus