Sorry, I don’t quite understand how it works firebase in Gdevelop. Namely “remove configuration”. How are they used? Help me please! And how do accounts work? How to manage them, how will the user register?
P.S.
I know there is an example, but I don’t quite understand it …
There’s the example, and there’s the wiki.
We can’t reexplain everything to everyone. 
So create yourself a Firebase account, play with a small project to understand how it works, check the wiki when needed, and come back here when you need specific help.
You see, the wiki does not say how and what to do, or how it works, it just says what can be done with firebase
Ok, tell me where is firebase configuration string?
This page indicates where the configuration can be found in the Firebase Console: Firebase Setup [GDevelop wiki]
Video tutorials on working with Firebase in GDevelop:
Perhaps they will help you understand the basics, and then you need to learn how Firebase works in order to use it for your purposes.
Thank you! You helped me a lot!