This is a multiple steps process :
1. Download the file "ASupermanFlightExperienceLINK.zip" from this website
2. Extract the files
3. Open the "READ ME.txt" file
4. Copy the link that is in the file in your internet browser
5. Click the blue button "DOWNLOAD (17.74GB)"
6. Now you need to wait for the file "ASupermanFlightExperience.zip" to finish downloading, it may take a while depending on your internet speed
7. Extract the files
8. Launch the "ASupermanFlightExperience\Windows\CitySample.exe" file