I’m not sure what that support engineer was talking about to be honest - Google Drive File Stream definitely does include the ability to work with your team drives: I think he must have been talking about Team Drives with the “normal” Google Drive Backup and Sync client.
Drive File Stream works by creating a virtual drive (G: by default in Windows) and under there are 2 folders: One for your Drive and one for Team Drives. You can right click on any drive / folder / file and make it available offline which then syncs it to your machine
We’ve been using it since the early access program and once you get used to it it is a far more flexible and powerful way to work with your drive / team drives.
Hopefully Insync will add support for team drives soon as it would be good to get the auto-conversion of documents, etc, but in the meantime I’m quite happy with Drive File Stream!