The Datto solution does not support Clustered Shared Volumes (CSVs) on any platform. This article explains the reasons why.
High Availability Cluster : A High Availability Cluster is a group of 2 or more bare metal servers which are used to host virtual machines.
Clustered Shared Volume : A CSV is a disk or pool of disks which is accessible by each node as if it were a logical disk on the system.
We are unable to directly support CSV backup processes due to the manner in which the STCVSM filter driver is read within Hyper-V. The filter driver ends up picking up an altitude that forces Hyper-V into redirected access mode when running backups. This is a shortcoming of the way Hyper-V interacts with its VMs, whereas vSphere does not pick up specific information about the driver versions in a virtual machine.