The Play Store relies heavily on "Google Play Services." If your Play Store is new but Play Services is old, it won't work. Ensure both are updated to their respective final versions for Lollipop.
If your device still feels slow after the update, consider a "Lite" version of your favorite apps (like Facebook Lite or Gallery Go) to keep the system running smoothly! google play store apk download for android 51 1 better
How is your after the update, or are you seeing a specific error code during the installation? The Play Store relies heavily on "Google Play Services
Staying on the "factory version" of the Play Store on an older device can lead to several issues: 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