The first step in mapping is the calibration of sensors. This is done by tapping the blue button at the bottom of the screen. Calibration involves first placing the device on flat, stable surface and then rotating the device around different access. MapCreator application will guide you through these steps.
The application may occasionally asks you to recalibrate, which is necessary as the sensor biases measured in this phase can change over time.
Note: If the percentage stays in 0%, in the first calibration phase, the device is either not stable enough or the gyroscope in your device is not a hardware sensor (see Supported devices)