Connect heart rate monitor chest strap to mobile phone?

Have the following heart rate monitor as a chest strap.

Now I would like to check my pulse via the app. The tracker can find my mobile phone immediately, but I can't find any app that can be connected to this device.

Or. No app finds the tracker.

Have the Huawei p20 pro, possibly. Does anyone have any tips "😊👌🏻

http://www.gpulse.com/en/product-353820/G-PULSE-BLUETOOTH-SMART-LOW-ENERGY-HEART-RATE-CHEST-BELTLED-HRM-BLE-200.html

Yes, I have the app, but the app can't find the tracker.