Ransomware recovery

Typical recovery of a major or total loss is to first restore the most recent snapshot prior to the event, then use a backup job to copy only newer or absent files from the remote backup (though there may not be any in your scenario).  That does the faster snapshot recovery first and only does the slower coping of files from the backup as needed.

For a small data loss, you can simply restore individual files or folders from snapshot if you know what they are, or you can clone a snapshot and then use a backup job to restore newer/missing files from the clone to the original share.  Since a clone is basically a visible snapshot, an alternative is to temporarily enable snapshot visibility and restore newer files from there, but I've never tried that using a ReadyNAS backup job.  If the backup is more recent, you can follow by a restore of newer files from it.

The risk of using snapshots for a total loss as a consequence of ransomware is that it usually encrypts the original files.  Since the new encrypted files differ from the ones in the snapshot, they will start to fill the available space and the NAS will start deleting snapshots if that space runs out.  So, that's a risk if you keep your NAS pretty full and is a good reason to make external backups as often as practical.