This is how it works for normal download and upload
--username --download googledrive:/Folder/ ~/
when it's a vault list works but any other command doesn't work you can upload to the vault but you can't download it you can interact with any subfolder of the vault you can just throw a file into the vault.
List command which work
duck --username --vault /Vault/ -list googledrive:/Vault/Folder/
Download which doesn't work
duck --username --download googledrive:/Vault/Series/ ~/ --vault /Vault/