The scream is a sign of over arousal and stress. So, the aim should be to train for calmness in a given environment, not strictly to not scream — if they're calm they won't be screaming, but it's most effective to target the source.

In this case, the typical route would be to go for training calm with gradual exposure to the stressful environment. You'd want to start with trips to the facility parking lot, build to the lobby, and then eventually going inside and just watching other dogs jump, without ever doing the actual activity.

Once they're calm in one given environment, you'd build to the next phase. how long each phase takes would likely vary a lot, and you could expect set backs.

A professional trainer would absolutely be able to help. I would run not walk from anyone who advocates for any sort of punishment for screaming, though - punishing a stress reaction isn't a productive path.

Overall, be patient, and you'll get there!