iMac Trade in kit missing label and instructions

You'll have to contact Apple, then, to have them provide a shipping label: Contact - How to Contact Us - Apple

If you did not get a return label, then you will need to contact Apple Support.

https://getsupport.apple.com/?

Typically, the return label is placed under the shipping label on the outside of the box.

Here's a YouTube video on how to package your Mac in the return box: How to Package Your Mac Trade In

Hope this helps.

You're not alone: did not receive return shipping label in my iMac return box - Apple Community

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