> No matching client found for package name '...'

Execution failed for task ‘:app:processDebugGoogleServices’.

No matching client found for package name ‘…’

this Error apears when i run my app (in visual studio, and android studio) after follow the description in this video: Ajouter Firebase à votre projet Android  |  Firebase for Android.
i want to creat a new firebase project for an andtroid app.
i dont know what to do.