Since you are downloading this outside the built-in update system, you must give your phone permission: Go to > Security . Find Unknown Sources and toggle the switch to ON . Tap "OK" on the warning prompt. Step 2: Download a Trusted APK
Even with a "better" APK, Android 5.1.1 can sometimes be finicky. If the Store crashes after the update: google play store apk download for android 51 1 better
Downloading a more recent (but compatible) APK ensures you have the latest security protocols for transactions. Finding the Best Version for Lollipop Since you are downloading this outside the built-in