Activated on Steam but cannot download

I have activated the game and supporter pack on Steam, and the game appears in my Steam library. However, it is not available for download - if clicked on, it displays the message 'this game has not yet released'. 

If I go to the store page, it shows as having released and is available for me to purchase as a gift (but not for myself, as I already have it in my library). 

This is troubling as it feels like an authorisation error. Any help would be greatly appreciated as I'm curious to see what the game is like.