Here is the guide on how to claim PUBG Royale Pass to upgrade your PUBG Mobile account:

1. Open the main menu by clicking the "Arrow" button on the lobby
2. Click the "Mail" button to open the mail from the successful transaction
3. Click the reward mail
4. The system will show you the item inside the reward mail, click the "Collect" button
5. Click the "OK" button on the notification page
6. Open your Inventory by clicking the "Inventory" button on the lobby
7. Click your Royale Pass Upgrade Card and click the "Use" button
8. Claim the Royale Pass by clicking the "Royale Pass Upgrade Card" button on the left side
9. The confirmation page will be shown, click the "OK" button to continue
10. Click the "Collect" button to finish

Done! The Royale Pass has been claimed to your PUBG account!

Happy gaming! 😉