Hello @BusybeingBizzie and welcome to our friendly community! Are you referring to the Odus challenge? You don't click on the reward box. Once the challenge is finished when you go to play the game the boosters should appear in your game. If they haven't appears, try clearing your cache, make sure you have the most recent version of the game and turn off your platform you are playing on (mobile or PC) for at least 10-15 seconds. When you turn the platform back on and enter the game - you should see the boosters.
If you still don't see them, then please let me know the make/model and software version you are playing with and also post your game ID "Find Game ID Number"and we will try and resolve this issue for you.