Is it possible to install the game in a non-default directory, say on a different drive? Or does it always install in C:\Program Files\...?
It is possible to choose where to install. To do that:
Click the blue thing next to the explore button.
In the window that pops up, choose Folders.
Then click on my software, to get a dropdown, choose My games.
there you can choose default path, and also tick of a box for promt for install directory.
Hit ok to save what you have done.