While OMNT should work without changes on the phone settings needed, there are some options useful to set for better measurement results.
The following settings can be found in the android developer settings menu. On Vanilla Android devices they are enabled by going to Settings -> About the phone and pressing there multiple times Build number. If this is not working on your device, a quick web search with your phone name and developer settings should help. After enabling the developer settings they are usually accessible via Settings -> System -> Developer Options.
- USB debugging: Install and debug apps via ADB
- Mobile data always active: Allows to gather mobile network information even if connected to WiFi
- Force full GNSS measurements: might improve GNSS accuracy while logging
Depending on your phone, there might be more useful options (or less)