In the standard Setup of CoDeSys there are no configuration files included for the PLCWinNT-SoftPLC.
In case you e.g. select the hard real time SoftPLC CoDeSys SP RTE as the target you could select several fieldcard modules such as the CP5613. For this Profibus fieldbus card you can append a sub element and configure its Inputs and Outputs. Thus you will have the physical I/O addresses available listed in the declaration of the global variables.
You can extend the available fieldbus cards and subelements (input and output nodes) by copying the Profibus GSD files in one of the configuration directories (specified in the menu Project / Options / Directories).
In case you just want to test the example without physical addresses but with the SoftPLC you can as well switch of the address check: Open the Target Settings dialogue (in the register card Resources) and highlight the register card "General" there. You will find the option "no address check" that can be activated.
By the way: In your example of the declaration you have to use unique variable names
. You forgot to rename the LEDs after copying them.