In this case, it is always necessary to proceed exactly according to the user manual.
1) First of all, check that the camera’s Wi-Fi is on in the settings.
2) Secondly, do not to launch the Wi-Fi application on your mobile phone, but instead find the camera in your phone's Wi-Fi settings and connect to it (the default password and Wi-Fi camera name can be found in the user manual)
3) Only by successfully connecting to the camera’s Wi-Fi, can the application be launched on your mobile phone