Where are filters on my range hood?
The website you linked to that sells the filters has this line in the description of the hood:


  ...a thin aluminum filter traps grease even before reaching the fan blades...


Based on the other diagrams of the product, the only place the filters can go is over the vane guards.  I guess there is a chance the filter sits right inside the vane guard, because the guard is described as "washable" as well, but that should be easy to determine once you have the filters.

Unless you do a lot of frying, the filters might not be necessary.  I assume that is why it is an optional accessory.