Depending on your system state, you may or may not have the game already installed. These resources should be useful starting points:
If you run into problems, it may be useful to remove all the files located in Documents\My Games\Runic Games\Hob\.
Note: We highly recommend that you backup your game saves to a safe location prior to performing an install or uninstall of the game. See Where are my saved games located? for more information.