Give some more info and I might be able to help - Does it crash every time you run it? Does it happen at a specific point? Does the quad still behave erratic?

First, try restarting your computer.

Make sure your graphics card drivers updated to the latest version.

Try running the simulator in a window by adding command line parameters to the .EXE file as described in the manual.

For example: 

-screen-fullscreen 0 -screen-width 640 -screen-height 360

If it still doesn't work, try downloading the entire .ZIP file again and unpack it. Try unpacking it to another location (Such as in a new folder in "My Documents" for example).

Here is a tutorial how to add command line parameters on Windows:

https://www.lifewire.com/command-line-parameters-video-games-3399930

(They explain how to do in on shortcuts - you can create a shortcut of Freerider by right-clicking the FPVFreerider.exe file and choose "Create Shortcut")

Here is a tutorial on how to update your drivers, for example your graphics card drivers:

https://www.windowscentral.com/how-properly-update-device-drivers-windows-10