Compatibility summary
You will need a travel adapter in Zambia; plug types used there differ from Germany.
Plug comparison
Germany plug types: C F
Zambia plug types: G
There is no common plug type between Germany (C F) and Zambia (G). You need a travel adapter.
Voltage comparison
Germany: 230V, 50Hz
Zambia: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.