I won the first Candy Royale race of 8 but never get the prize

Hello @Ostrich and welcome to the community!

There have been reports from others about problems claiming prizes from this event and some other events, and this has been going on for a very long time. The whole game of Candy Crush is full of glitches and technical problems that players have to put up with if we want to play. One problem that might have caused you to not get your prize immediately may have been that you had temporarily lost connection to King's server at that point. Losing connection to the server is a common problem for many. I fear that at this point there is probably nothing you can do to retrieve the prize that was not awarded two days ago. Player Support might give you a few boosters as compensation but I have heard that they are not very helpful for such cases especially if you have no evidence of how much you won. I don't think the game keeps a record of that. So for the future I would suggest to take a screenshot when you win the event, just before you press the claim button. The event often goes wrong and it's best not to trust it. Don't spend a lot of gold or real money on the expectation that you will win the prize. I never trust Candy Royale to pay out until I see the gold in my account!