There is no automatic mapping between a LV cluster and a .NET structure. You'll need to unbundle the cluster and set each property/field of the structure one at a time. Of course, in the example you posted, there isn't a need to create the cluster in the first place, but if you do accept the cluster as an input parameter to a VI, you'll need to unbundle it.
Basically, if your invoke node or property node show a LV data type, then you can wire a LV native type in. If it's that thin, green refnum wire, that means you'll need to use the property or invoke nodes on it to set or get any data.