Perhaps because it isn't officially released until the 24th? The early download is probably to spread out the network load rather than all the pre-orders trying to download at the same time.
It is a pre-order so it has downloaded the game but it is not active because it's release date is July 24th. once July 24th comes around it will become active.
How and or where did you get to download the game for PS4? It does not appear in the Playstation store here in the U.S. I have followed the upgrade path link in the announcement email, but once I get to the U.S. Playstation Store, the option to preorder the game is not available.
This is being done to cut some slack on the servers to be honest! I read that many other publishers are doing the same.
I'm afraid Sony US doesn't do pre-order for non AAA titles. All we could do for the US was offer pre-ordering from Amazon, GameStop and Best Buy. It'll become available in the Playstation store in America from tomorrow.