when I push the right turning knob it's telling me that the guidances is not activated.
This is normal. This message tells you you are not "currently" following a route. It does not mean the Navigation is not functional. Pressing the right hand knob, recalls the last Navigation instruction provided by the system. If there is no last instruction, as in the unit is not currently navigating, the response is "The Guidance System is Not Active". Don't misread this as the guidance system is faulty, which it is not.
Being a 2004 you will not be able to integrate the RNS510 into the dashboard or steering wheel controls without a CAN Bus "Bridge". The 2004 is running CAN Bus Version 1.6, and the RNS510 requires CAN Bus version 2.0 to talk to the car. Send a PM to Dragline1570, who may be able to assist with the supplier of an interface "bridge" in Germany. Without that the Car and the RNS510 cannot talk to each other.
Stuart...