For Android 5.1 (Lollipop), you can download the Google Play Store APK from reputable third-party mirrors, as Google does not provide direct "download" links for the app itself. The most compatible versions for your device are typically those labeled for Android 5.0+ (API 21). Recommended Download Sources
While the Play Store APK itself is safe, Android 5.1 has not received security patches since approximately 2018. By updating the Play Store, you reduce app-related risks, but the OS kernel is still vulnerable to exploits like BlueBorne, Stagefright 2.0, and Janus. google play store apk link download for android 51
com.android.vending_30.9.52-21_240913100_minAPI21(nodpi)_apkmirror.apkStay safe and happy downloading!