Sometimes you may get an unable to download error in Google Playstore, and this can be caused by various factors. play

For me the reason I got that error was I was in a state or i.p. address that the app doesn’t do business with so I suspected that was most likely the reason why I got that error.  Some of the error codes you may encounter can be 919, 419, 923, 498,  492, 495, 403, 24 and 920

To fix one of these Play store errors Go to Settings > Accounts > Google and remove your Google account. Then add it back to the device and try re-download the App. If it doesn’t work and the error is still there give it some time. It’ll likely clear itself out and you’ll be able to download the App later.

You can also try:

Going to Manage applications on your phone settings, and then find Google Play, then press the “Force stop” and finally “Clear Data”.

Sometimes waiting 10 minutes and attempting another download is the best idea because that worked for me once. Error could be caused by you experiencing network issues even if you are not aware you are.

You can also download Kies if you are on a Samsung android phone and update your phone.  Updating any smartphone will have positive effects.