Syncing harddisk to NAS

My Cloud OS 3 Personal & Network Attached Storage My Cloud EX2
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I am still trying to understand how to get the most out of my EX2. One thing I would like to do is to sync the files in the public share of the NAS to a hard drive at another location.
One easy way would be if I could mount the NAS remotely as a drive on my Mac, rather than just opening it in a browser. Then I could run a sync app on my computer between the USV-connected drive and the remote NAS.
I could also sync via Dropbox, though I am not sure how to set that up so it syncs that one folder on the NAS.
And finally I guess there could be specific syncing apps that run on Mac that might do this.
Is there anyone out there who knows more about this??