MS store of steam? If its steam make a new steam library on the new drive then choose that library for the install … OR you can start the game from the launcher, when it gets to the update screen and asks you where to install to: click on the location slot on the bottom right of that page, a popup will appear asking you what dir to use. From there point it to the new drive and let it rip, if you do this the second way you should have a launch dir on you C: drive and the Game in say D:\msfs.