The folks at Sound Particles reached out a while back to chat about all things crowd related. From our efforts on FIFA to the Atmospheric Audio project and what we did to help provide crowd audio for real life matches.
I tried to keep things generic and helpful to as many folks as possible, but stoked for the opportunity to chat and share a bit of insight on the subject. Hope others find it useful, you can check it out here:

https://blog.soundparticles.com/how-paul-boechler-created-live-stadium-crowds-from-fifa-recordings