Hi Georg,
Although more than half the Ericaceae on the planet are indigenous to South Africa, I only know of one species of Vaccinium. It bears edible, though small, berries like the cranberries and blueberries. No other local member of the family is significantly edible. However, some imported species of cranberries, cloudberries, blueberries etc are grown locally, and so are various imported members of the Rosaceae, including blackberries, loganberries, raspberries and so on. They are mostly members of the genus Rubus.Some of them have escaped and grow in mountain gorges and similar places.
We do have several indigenous species of Rubus, and they do bear typical blackberries, but they tend to be smaller and to bear berries more irregular in yield and size than the commercial varieties. Birds feed on them of course, and spread their seed accordingly.
Much as in Europe, but the thickets tend to be limited to moist, cool spots, which are commoner in northern Europe than in South Africa!
I hope that is what you wanted to know?