For reference: https://www.hitachivantara.com/en-us/products/storage/network-attached-storage-platform.print.html
HNAS supports a 1PiB filesystem and 1PiB span, so your single CIFS share conceivably could be 1 PiB, though many people use ViVols/quota's to limit the view to the client.
Are you actively in a migration project moving from VNX to HNAS? if so, we usually have GSS work with the client on migration projects.