This error is displayed when there is an incomplete purchase.
Try the following:
・Restart your device and complete the purchase:
1. Start the Mario Kart Tour game.
2. Tap Shop at the bottom of the screen.
3. Scroll to the bottom of the page and tap Complete Purchase.
・Clear the cache for the Google Play Store on your device.
・Clear the cache for Google Play services on your device.
・Cancel pending purchases in the Google Play Store:
1. Open the Google Play Store.
2. Tap the circular icon at the top right of the screen.
3. Tap "Payments & subscriptions."
4. Tap "Budget & history."
5. Cancel any pending purchases.