The error message seems to be caused by a temporary file used during installation, and doesn't get deleted for some reason. Because of this, the system can't use it and treats it as an error. If the problem re-appears, you may need to perform the operation again.
Here's how you do it:
1. Go to Settings and click on Storage
2. Scroll down to where you have Unmount SD card and tap on it.
3. Now go back to the Play Store to download the app again. This time, the app would be installed hopefully!
4. After app is installed, you can go back to the Storage settings and tap Mount SD card
5. After mounting, you can move application to SD card if its possible. Some apps can't be moved to the SD card and some can.
Don't have an SD card?
If you don't have an SD card you could try to clear your Google Play cache. You do this by going to the Google Play settings and clear cache.