Ok so this happened to me (using a macbook air) and I just figured it out but it requires an Apple TV or other device with larger screen, but basically you need to connect to the Apple TV/other device using AirPlay (open up System Preferences --> Display --> Airplay Display). Then once you've shared your laptop screen, change "Optimize for" to the name of your apple TV/other device. This will shrink the windows so you can access the "place order" button.