doesn't build

[sgehrman]

steve@tr4:~/google/MQuote$ flutter run
Running "flutter pub get" in MQuote... 4.7s
Launching lib/main.dart on ONEPLUS A5010 in debug mode...
[!] Your app isn't using AndroidX.
To avoid potential build failures, you can quickly migrate your app by following the steps on https://goo.gl/CP92wY.
Project evaluation failed including an error in afterEvaluate {}. Run with --stacktrace for details of the afterEvaluate {} error.

FAILURE: Build failed with an exception.

• Where:
  Build file '/home/steve/google/MQuote/android/app/build.gradle' line: 29

• What went wrong:
  A problem occurred evaluating project ':app'.

/home/steve/google/MQuote/android/key.properties (No such file or directory)

• Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

• Get more help at https://help.gradle.org

BUILD FAILED in 3s
Running Gradle task 'assembleDebug'...
Running Gradle task 'assembleDebug'... Done 3.8s
Gradle task assembleDebug failed with exit code 1