Surface mounting an exhaust fan that is meant to be in the wall

Ductwork comes all the way through a concrete wall, it is probably 50 years old, they used thick sheet metal, would be very difficult to modify.

I think I need some kind of an external mount box to go over the hole and be able to house the fan, does something like this exist or do I need a different kind of fan that isn't supposed to be recessed like the one I linked.