Using a Service Account as a secondary 'backup' 750GB quota

Hi,

I have a question about using a Service Account as a secondary 'backup' 750GB quota.

Here's the part I don't get: after the Service Account is created, the API is added by GSuite admin and the json is downloaded, there still needs to be an 'auth' with the existing Google Account to be able to access the existing drive - the 'access token'.

Rclone --drive-impersonate user@gdrive.com will achieve this and allow access to an existing account, but the main account upload limit is still in place as you have to identify to the existing drive in order to be able to access that drive.

What's the part I'm missing?

If a Service Account should have a 750GB upload limit, how do you access an existing encrypted drive WITHOUT identifying using the credentials which have already passed that 750GB limit?

Here's my Rclone config for the service account:

[gdrive]
type = drive
scope = drive
service_account_file = C:\Users\my.json
token =

Thank you