Snapshot Destination in snapshot plugin

Hi, we're studying the backup types so we can proceed to apply it systematically to all our new sites (we're new in WPMU).

1.- Managed backup: We won't use it, since it's very expensive, also we use to have our servers and nodes.
2.- Amazon S3: We never used Amazon S3, but created a new account in there but even with so many documentation, we don't know how to create a user to give permissions inside a bucket that we created
3.- Google Drive: We have a 1TB account standard Google Drive connected to one gmail account, but not using Google Cloud. Is there any way to use this ? Plugin is requesting to go to Google Project Console.

Thanks