Macbook Air not showing source code

I'm migrating from my MacBook Air to an iMac. When I've chosen my MacBook Air it tells me to wait until the code pops up on my MacBook. The code never seems to pop up on my MacBook Air. I've rebooted my router, and both devises. Some help would be splendid!

What I'm doing:

Migration of internet
Both devises are up to date

My older devise has limited space

I've set up all my iCloud and iTunes information

-Mida