All download and billing-related problems should be taken up directly with Apple as developers aren’t given access to troubleshoot that part of the platform. We merely submit our games to the store while Apple handles their sale and distribution.
However, there are some steps that we can go through before you contact Apple.
1. Restart your device
2. Open the App Store
3. Tap your profile picture in the top right corner
4. Tap “Purchased”
5. Tap “My Purchases
6. Find the game in the list of apps that appear – you should be able to download it from there
If the problem continues, please use the following link to try to find a solution to this problem and ultimately contact Apple: https://support.apple.com/apps