The game can be updated in 2 ways: automatically or manually.
You can find the instructions on how to update the game on your platform below:

iOS

1. Open the App Store on your device.
2. Tap the Updates icon on the bottom panel.
3. If a new update is available for your game, it will appear in the list. Tap "Update" next to the update description to download it.

You can also change your device settings to automatically download updates for the apps you have installed:
1. Go to Settings -> iTunes and App Store.
2. In the Automatic downloads section, turn "Updates" on.

Google Play

1. Open the Play Store app on your device.
2. Tap the Menu icon in the top left corner, and then "My applications and games".
3. Find the game name in the list and tap it.
4. Tap "Update" when the game page opens.

You can also adjust your device settings to automatically download updates for the apps you have installed:

1. Open the Play Store app.
2. Tap the Menu icon in the top left corner.
3. Go to the Settings section.
4. Tap "Auto-update apps".
5. Choose one of the following:
- Auto-update apps at any time. Updates will be downloaded via both Wi-Fi and your mobile network.
- Auto-update apps over Wi-Fi only. Updates will only start downloading when your device has a Wi-Fi connection.

Huawei App Gallery

1. Open the App Gallery on your device.
2. Tap the ME icon in the lower right corner.
3. Choose "Updates".
4. Find the game in the list and tap "Update".

Amazon

1. From the Home screen, tap "Apps". 
2. Tap the menu icon in the bottom part of the screen, and then "App Updates" (or "My Apps").
3. Find the game in the list and tap "Update".

Microsoft Store

1. Open Microsoft Store.
2. Click on  "Library".
3. Choose "Get updates".