Here is How you can install Kodi 17.0 Beta2 from Microsoft App Store, step by step guide, a few little pointer when you are trying to install and you see the button is gray out. do not worry check these steps.
1. Windows is up to date.
2. Did you install Microsoft Anniversary update for Windows 10?
– To check for update on windows 10 Click On Start//Settings//Updates and click on Check for the update.
– to get The Anniversary Update simply visit http://aka.ms/winup
** Make sure you have about 20GB free space in C Drive