I have downloaded the game and installed it without errors. On Windows 8, the only requirement is that you need to be logged in with an Administrator user. Once you have the installation package, right click it and choose Run as Administrator, then if it's possible, choose another partition to install the game.
To obtain the latest installer, visit the following URL: https://www.asheronscall.com/en/content/downloads
Note: I have used Windows 10 x64 and it worked normally.