Set PlayStore release configuration in app/build.gradle file

build.gradle

...
android {
    ...
}
play {
    track = 'alpha' // set track for playstore  like 'production','beta','alpha'
    serviceAccountEmail = '[email protected]' //paste your service account email
    jsonFile = file('/PlayJson/play-store-key.json') // copy this line as it is do not modify
}

dependencies {
    ...
}