If it has been longer than an hour or other members of your guild have said they received their rewards, you may not have met the individual requirements (personal points) for the Rumble rewards.
Your guild's rank will determine which rewards everyone in the guild can receive. However, there is a personal points requirement as well. This is to ensure that members of the guild have to "pull their own weight" in order to get the event rewards.
To double check how many personal points you have contributed, go to Rumble Island in-game and tap on the scores icon in the bottom right. Then, navigate to the Points tab and find your name. The number next to it is the total points you contributed to the Guild Rumble.
The Guild Rumble FAQ contains the full reward information. If you did not contribute enough personal points to quality for your guild's tier rewards, then you will not get those rewards. You will receive up to whichever tier you personally reached.
If you reached the minimum point requirement but still don't have the reward message after an hour, please contact support. They will check on what went wrong and be sure to send you a correction if needed.