Hello! I understand you're having trouble installing the Heart of Vegas app on your Kindle with Android 9. Let's dive in and get this sorted out.

To start, could you tell me a bit more about what happens when you try to install the app? For example:
- Are you downloading from the Amazon Appstore or Google Play Store?
- Do you see any error message during installation? If yes, what does it say?
- Have you checked if there's enough storage space on your device?
- Is your internet connection stable during the download?

These details will help me tailor the steps to your situation.

Meanwhile, here’s a basic step-by-step checklist you can try:

1. Restart your Kindle device: Sometimes a simple reboot clears temporary glitches. Hold down the power button, turn off the device, wait a few seconds, then turn it back on1.

2. Check Storage: Go to your device settings, then Storage, and make sure you have enough free space for the app.

3. Clear app store cache: If using Google Play Store, go to Settings > Apps > Google Play Store > Storage > Clear Cache and Clear Data. For Amazon Appstore, you can try clearing its cache similarly.

4. Update your system software: Sometimes older OS versions can cause compatibility issues. Check for any system updates available under Settings > System > Software Updates.

5. Download and install again: Try downloading the Heart of Vegas app fresh from your app store.

If after this the problem persists, please share the error or behavior you see, and we can look at deeper causes such as device compatibility or account settings.

Are you able to try these initial steps and let me know how it goes?