Android Studio App keeps crashing on some devices

I have written a simple android application using the Google Maps API. It works flawlessly on some android devices but fails/crashes on other devices. In the project creation wizard of Android Studio and in the minimum compatible OS, I choose Kit Kat OS for wider compatibility. The build.gradle is listed below. Currently I can't test on AVDs due to my IDE settings. How can I resolve this issue?

android {
compileSdkVersion 29
buildToolsVersion "29.0.2"
defaultConfig {
    applicationId "com.example.unitstatus"
    minSdkVersion 19
    targetSdkVersion 29
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

I distributed the apk through WhatsApp messengers to my clients. Client's Android setting need to be set to 'Allow third party library' to continue the install.

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