SLPRO Start/Stop button installation

Hello, I and my father would like to install a Start/Stop button system, I am a car and NFZ mechatronics engineer and know me well with electronics and electrics. Well, I/we have decided for a Start/Stop button which includes a safety circuit that you can not start again during the running engine. Therefore, I bought a Start/Stop button from SLPRO at ebay. Unfortunately, the English manual is poorly translated. nte, I used to connect it to a 12 volt power supply to measure when where current flows. Once it worked, but now the switch doesn’t do anything anymore. Since you can also integrate the Start/Stop button into an alarm system, I’m not sure if I now have a think factor. Since I don’t know where to connect it to a cable. So my question, has someone already installed such a switch here? on the pictures the system is itself and the V cabling instructions to see. MFG