One of the small elements surrounding the "Ubisoft Forward" presentation was a planned giveaway of various items for different games across Ubisoft's catalog, including a free copy of Watch Dogs 2 on PC. Ostensibly, all people had to do was log in to their Uplay account, watch the stream for a certain amount of time, and unlock the corresponding reward.
Of course, things didn't quite work out like that. Login servers were hammered flat, causing a large number of people to be unable to log in to obtain the rewards. When that failed, Ubisoft tried an alternative method involving key codes.
However, the same server issues which prevented people from logging into their accounts also hindered the ability to redeem key codes. Ubisoft, to their credit, seems to have recognized the problem and has arranged for a second alternative redemption method, stating that the rewards would be going out to everybody who wanted to claim them.
The steps are pretty simple.
You should get a confirmation message thanking you for tuning in to Ubisoft Forward.
There are a couple of caveats. First, the PC copy of Watch Dogs 2 is going to be locked to your Uplay account, so it's necessarily going to be available only through the Uplay client, rather than Steam or EGS. Second, while you may get the confirmation that the rewards have been claimed for your account, they're not going to appear in your Uplay library immediately. Watch Dogs 2 will be appearing sometime over the next couple of days.
The other rewards are predominantly for games that won't be out for a while yet. The only exception is the apparel cache keys for The Division 2, though much like Watch Dogs 2, the actual appearance of the reward may be delayed.