The VirtualSystemType in the OVF is a list of hardware types that the bundled appliance supports. The installer should pick the best one that it supports from the list, and only consider erroring if there are no entries that it can support.
https://www.dmtf.org/sites/default/files/standards/documents/DSP0243_1.0.0.pdf page 19 line 657
The vssd:VirtualSystemType element specifies a virtual system type identifier, which is an implementation defined string that uniquely identifies the type of the virtual system. For example, a virtual system type identifier could be vmx-4 for VMware’s fourth-generation virtual hardware or xen-3 for Xen’s third-generation virtual hardware. Zero or more virtual system type identifiers may be specified separated by single space character. In order for the OVF virtual system to be deployable on a target platform, the virtual machine on the target platform is should support at least one of the virtual system types identified in the vssd:VirtualSystemType elements. The virtual system type identifiers specified in
vssd:VirtualSystemType elements are expected to be matched against the values of property VirtualSystemTypesSupported of CIM class CIM_VirtualSystemManagementCapabilities (see DSP1042).
The installer gives a warning that it found an unexpected virtual hardware type with the entire list as a string as if it were one item. If does however allow you to skip past it and install anyway.