Hey guys, thanks for getting in touch and sorry to hear about the issue you ran into.
To find more details about the event and it's conditions as well as rewards, have a look at the following articles:
1.
Artice 1
2.
Article 2
Once you complete the challenge, in order to redeem your reward, go to the Ubisoft Club tab in-game or the Ubisoft Club mobile app. You will have six weeks after the challenge is completed to redeem your reward.
In case if you are still missing your rewards, please let us know which exact reward you are missing (I already know what xantys.iv is referring to) and provide us with screenshots of the region of the inventory, where the reward should be.