Did you created project in firebase ?
Yes but I downloaded this file from the internet that means that the app uses the project created by the actual developer in firebase
Most probably the actual developer deleted this project from firebase. Create and use your own
In above image I see that you have a project in firebase since you have access to firebase’s console
Post a screenshot of your firebase
Here you go, but the project that the developer used is different from that of what is shown in screen shot …the name of his project is = com.ots.maxproearn
Screenshot 1
Screenshot 2
The firebase that you are using in your project is https://my-earning-a1337-default-rtdb.firebaseio.com and from the name of it looks like you are trying to make an earning app which is not allowed in Kodular.
Unless you create a new firebase realtime database correctly no one can help you. Follow the guide for beginners and link correcty your database in creator (firebase token, firebase url, project bucket). Once done if you still encounter errors post for help.