Does each Hyper-V CSV Node Require a License?

You’ll need a Server Edition or Server Enterprise license and installation on each node and each node should use its own target folder, whether or not going to the same target device. The deduplication algorithm works on a file basis, meaning each file (VHDX) is deduplicated on its own in isolation. You would set up a schedule (daily, weekly, etc) on each node for the VMs it owns and once it’s set up it should be fine.
If all CSV nodes use the same network target you may want to space backups apart a little to avoid network collisions, which reduce overall network bandwidth, unless you have a direct connection to the target. On a Windows Server 2008 and R2 you don’t have a choice, you must space backups apart as they are not permitted to run simultaneously. The best strategy depends on your exact setup, available bandwidth, total bytes being backed up, etc.