Not sure where this properly belongs, but I see one or two similar questions in Mac & Linux Products
Thread moved from Community Support to Business > Endpoint Security > Mac & Linux Products for attention.
Looking at the supported products page for 5.9, VSEL isn't listed as a supported product.
Looking at the VSEL supported environments page, EPO 5.3 was the latest supported version:
ePolicy Orchestrator (ePO) support
VSEL Version ePO Version VSEL 2.0.x ePO 5.3.x, 5.1.x VSEL 1.9.x ePO 5.3.x, 5.1.x