You only select the Bucket. All backups are organized within the bucket based on computer prefix. Folders in the cloud are not like folders on your hard drive. Cloud objects are stored in a flat file structure - the folders are themselves just objects and AWS prefixes folder object name to the file names of those files that are stored within them to make "browsing" more like a traditional hierarchical file system.

So, all you need to do is select the Bucket you want to use or create a new one, as needed. You can read more about S3 "folders" here: https://docs.aws.amazon.com/AmazonS3/latest/user-guide/using-folders.html

Thanks David. I should have provide more detail. What I was looking for is the option in the PC Backup under 'Custom' where you can select a Folder in the Container. This is not available on the MAC version yet I've been told.

However, on PC, you can save to a specific folder in a Container in a backup plan.