If your built-in Play Store is not updating automatically, you can manually download the compatible APK from these trusted repositories: APKMirror - Google Play Store
Android 5.1.1 (Lollipop) was released over a decade ago. While it is considered a "legacy" OS, millions of budget phones, tablets, and POS systems still run it. Unfortunately, the built-in Play Store self-update mechanism often breaks due to: If your built-in Play Store is not updating
By following these steps, you should be able to download and install the Google Play Store APK on your Android 5.1.1 device. However, please be aware of the potential security risks and use trusted sources for downloading APKs. millions of budget phones