Looks like Google deployed an employee-only version of Google Drive, which is apparently being renamed to Backup-and-Sync [1]. The result is that the new Backup-and-Sync app comes up with a "Sorry, the app needs to close, please email @ to get your account whitelisted" -- meaning, apparently, that the app is restricted to Google employees.
I went looking for info and the only reference to the error I could find was one Reddit thread. Thought HN readers might want to know what's up as well -- and hoped that maybe someone at Google might notice this and fix it ASAP, please, because I am using Google Drive as part of my workflow right now? :)
[1] https://www.reddit.com/r/google/comments/5zrwwp/google_drive_is_now_backup_and_sync_error/