13 inch MacBook air with apple M2 chip

The code should appear on the older Mac — the one from which you want to transfer information to the new one.

Transfer to a new Mac with Migration Assistant - Apple Support

If it does not, then the two Macs have failed to establish communication.

Did you have encrypted your disk with FileVault? Then it is asking for that code

Did you have a firmware password on your Mac? It could be that it is asking for that code as well

Ok thanks. In that case the usual culprit is a Windows "anti-virus" program or "firewall" that prevents communication with devices unless you explicitly allow them. Unfortunately I can't offer much more than that general advice since I don't use PCs.

Fortunately Apple ought to be familiar with what you need to do. Contact them using the link below, and have them talk you through it. Complimentary phone or chat support is included in the price of your new Mac. Tell them what you need to do and they'll be happy to help.

Official Apple Support