1. Cirilla version not compatible with App builder.
What is going to happen if you using Cirilla app not compatible App builder plugin.
We design the app builder to work with Cirilla app, but over time we alway upgrade, fixes and improve on both platform. So if you using the version not compatible. Overall the app still working but some feature not working on show errors.
So to use compatible version you need check our change logs to see detail what we fixed, improved or remove
Our change logs can found here: https://appcheap.io/category/changelog/
2. Flutter version not compatible
If you can’t run the app or build the APK you can thinking about this we also notes the version compare here
If this is first time you working with Flutter ensure you setup run example Flutter app first:
https://docs.flutter.dev/get-started/test-drive
3. Conflict other plugin
The App builder plugin can be conflict other plugin so the app will not working
You can disable all plugins except App builder, if your app using Woocommerce so except App builder and Woocommerce plugin.
4. PHP errors
You can enable debug mode on WordPress to get detail error in PHP code.
https://wordpress.org/support/article/debugging-in-wordpress/