HEY ALL! I DID IT!!
I got email confirmations from Microsoft saying they fixed the problem and they did!! You can now download Halo Wars DE onto your PC even if you bought a physical copy of HW2. Go to the MS store on your PC and find the HW2 bundle and click the Halo Wars DE and it SHOULD say install. It worked for me and hopefully they fixed this for everyone and not just me but they did say it was a widespread glitch.
Sorry I didnt post this in the original thread… I am too lazy to find it and would rather people know whats going on. If its a problem, make an admin thread and sticky it or something.