The enclosure passes the disks individually to the operating system. It does not offer hardware RAID. Each hard disk can thus be S.M.A.R.T monitored.
I find a RAID solution directly at file system level (e.g. btrfs) or software RAID (mdadm) more convenient, as you can simply move the disks as you wish (if the enclosure dies). The NAS's also do this.

I'm currently doing some research, including this article. A Raid will not be possible with this device. The Raid must be taken over by the device that is connected to it.