Hi stanleyfrombutterworth,
Since it does appear that Clash Royale is available in Malaysia, let's make sure your region is set correctly using the steps in they resource: Change your Apple ID country or region - Apple Support
- "Open the Settings app.
- Tap your name, then tap Media & Purchases.
- Tap View Account. You might be asked to sign in.
- Tap Country/Region."
If you are currently in Malaysia and that is what shows in your region settings and you still have the issue, let us know if you get any new alerts or error messages when trying, as those may help us determine what might be causing the issue.
We also recommend restarting your device and keeping it updated as those steps assure you have cleared out any minor software issues and are running the most current version.
Restart your iPhone - Apple Support
Update your iPhone or iPad - Apple Support
If you still have questions, reach out to Apple Support directly, as this may require closer guidance: Get Support
Cheers!