In many cases, the camera connects automatically after entering your Wi-Fi details, without needing to scan the QR code.
If that doesn’t work and scanning is required:
Set your phone’s screen brightness to maximum, hold the phone about 15 to 20 cm from the camera, and make sure any protective film is removed from the camera lens.
Try scanning in a well-lit environment and move the camera slowly toward and away from the screen until the QR code is recognized.