First please set the Key connection to the Lock as shown in the following article on connecting to Siemens PLCs:

To be able to connect to WinCC from Simatic Shell please follow the following steps:

Step 1: Open “Simatic Shell” folder. (This PC\Simatic Shell)
Step 2: In the window that opens, right-click on “Simatic Shell”

Step 3: Chose “Settings”
Step 4: In the window that opens “Comunnication Settings” set:
  • Network adapter selection: Tosibox TAP-Windows Adapter
  • Multicast Proxy: IP Address of the PC with WinCC SCADA

Now the WinCC SCADA should be visible.