This seems like a small enough data size that it shouldn't cause the sort of issues you're seeing, especially since you're not collecting media files. When you download the .zip file, then unzip the .csv file, what is the size of the .csv file?
I'm realizing that what you describe sounds similar to this topic:
If possible, it'd be very helpful if you could share some of your server logs with us. (You can send them via a direct message to me or anyone else on the core team.) To retrieve those logs, first trigger the issue by attempting to download the CSV file, then waiting for the error. Next, follow these steps to retrieve the logs from that time period for the service and nginx containers. I suspect that anyone on your team who tries to download the unzipped CSV file will encounter the same issue you're seeing.