Thanks, I can see the problem. Your family contains over 250,000 people and is hitting some internal server limits while the download is being prepared. I'm afraid we can't raise these limits without risking general system stability. For now we'll have to help you with occasional downloads – on your request (via the feedback form) we can download your family to a file and share it with you via Google Drive. The longer term solution will be the infrastructure upgrade that is coming...