Google Drive API: The user has not granted the app error

Once you go through the Quick-Start Tutorial initially the Scope is given as:

SCOPES = 'https://www.googleapis.com/auth/drive.metadata.readonly'

So after listing files and you decide to download, it won't work as you need to generate the the token again, so changing scope won't recreate or prompt you for the 'google authoriziation' which happens on first run.

To force generate the token, just delete your curent token or use a new file to store your key from the storage:

store = file.Storage('tokenWrite.json')