There are many possible reasons as to why the game cannot be updated or installed like corrupted files or system caches. You can resolve most of these issues by following the basic troubleshooting steps provided by Steam through the link below:

https://support.steampowered.com/kb_article.php?ref=2274-IFLV-5334

Also, the game is currently available for North/South America. Players in other regions who are interested in downloading the game will not be able to do so until its scheduled release: early June for Europe/MENA and Asia/OCE.