Run the windows troubleshooter.
Start menu - "troubleshoot" - click on "Windows Update" - let the troubleshooter run while the MS Store app is closed. Once complete, try the download again.
If that doesn't work restore the cache. Close the MS Store app - Start menu - "wsreset" - run as administrator. The store will reboot after a few moments. Try the download again.
If that still doesn't work, go into your user files. Go to "C:\Users\user_name\AppData\Local\Packages\Microsoft.WindowsStore_8wekyb3d8bbwe\LocalCache" and delete all the files. Reboot MS Store and try it again.