But now the part, where I am currently struggling with: I don't exactly know, what the next steps are to get for example the actual position data of the robot and further proceed this data in twincat or in general see some data from the robot in twincat. Maybe you can give me a hint how to proceed on from my current situation.
Well, to start with, what signals have you mapped in WV? Whatever $OUTs you have mapped to the PLC, if you force one on from the pendant (teach mode, deadman held, motors on are prerequisites), you should see the corresponding input on the PLC change state to match.
Likewise, whatever the first PLC output you mapped in TwinCAT to the robot, if you force it on in the PLC, you should see the corresponding $IN on the robot change state to match.