Fix Build Issue & Integrate IAP

I need help resolving a build failure after integrating 'react-native-google-mobile-ads' in my React Native Expo app. I've followed the setup instructions exactly but am encountering configuration errors.

Additionally, I require assistance integrating in-app purchases.

Ideal Skills & Experience:
- Experience with React Native and Expo
- Familiarity with 'react-native-google-mobile-ads'
- Strong understanding of configuration issues
- Experience with in-app purchases integration