If you see “192.168.4.1” — that means your controller is still in AP mode and it has not been connected to your home WiFi yet. In order to access the page of 192.168.4.1, you need to connect your phone or laptop to the OS_xxxxxx AP. Please refer to the user manual, or the one-page getting started guide. These steps are clearly described in the user manual and instructions.
The current firmware allows all firmware features to function in AP mode. So in the case you don’t have a WiFi router, you can have the controller remain in AP mode, and use your phone to connect to its AP. Then use the OpenSprinkler mobile app to communicate with the controller.