You get an email with a link to the Google Play store with your order. You have to use a credit card to finish the order. It was $860 + tax, no shipping charge. That same email includes a PDF file which you print for the prepaid return label. Then you can watch your order as it's being processed and eventually you get an email with a shipping notice and tracking data. They ship 2day Fedex but with special instructions to only deliver Mon- Fri.Did they give you a tracking number first or did it just show up?
Hours after I shipped the 6P back I got a notice from Google that they saw I shipped the phone back and the charge on your credit card is gone. They don't really charge your card, they just ping it for the amount, if you don't get it back to them then I assume you will get charged.