There are wild red deer in the whole Veluwe area, de Meinweg and since a few years the forest near Weert. The problem is that red deer were favoured hunting material, so I wouldn't be surprised if there were many man-made introductions in the past hundreds of years. There should be some research on Dutch red deer genetics online. If they are "pure & original" stock, they should belong to the elaphus/hippelaphus (which includes germanicus) subspecies, depending how many subspecies you recognize...