Unable to flash px4 into Pixhawk CubePilot CubeOrange+

I’m trying to load firmware onto Pixhawk autopilot flight controller, but unfortunately in one of the early steps I’m unable follow the given instructions.

Along the Firmware Setup tab of QGC results an error as follows:
‘Found device: CubePilot
Error: Open failed on port ttyACM0: Permission denied
Upgrade cancelled’

Meanwhile the terminal that runs QGC gives the following:
“open failed “Permission denied” QSerialPort::PermissionError “CubePilot on ttyACM0 (AutoConnect)” autconnect: true”

When tried to run the QGroundControl.AppImage with sudo admission, QGC didn’t run and returns suggesting try following commands in case of port errors with Ubuntu/Linux:
sudo apt-get remove modemmanager -y
sudo usermod -a -G dialout $USER

And as you might guess, no successful results with there either.

What you would suggest me to go onto it with?

There is an issue with QGC v4.4.4 . You cannot flash CUBE Orange as well using windows platform. The way forward is to use QGC v4.4.4 through Ubuntu platform.