If you follow the steps in the link provided, in that sequence, then it’s correct that when you first put the project into PLAY mode you will get a “Hardware offline” message,
That’s because the next step in the process is to upload the sketch, with the newly acquired auth code, to the hardware.
When the hardware boots it will connect to the internet (in your case via the USB script) then to the Blynk server. At that point, the hardware will be online and show as online in the app.
The PC running the script needs to be on, and connected to the internet at all times, and the script needs to be running in an active command prompt window at all times, for the device to be connected to the Blynk server.
You’ve made life difficult for yourself by choosing the USB connection method, as this uses the serial port, so you’d need additional hardware in the form of an FTDI adapter to see the serial monitor data which is being sent to the SoftwareSerial pins. This additional data would probably help you to diagnose why your connection isn’t working.
One think you could try is editing the script to use port 8080 instead of port 80, as your ISP may be blocking traffic on port 80.
If you’re going to do some more serious IoT projects then you should use a board that has built-in internet connection capabilities. They are also cheaper than the Uno that you’re currently using…
Pete.