In app.json instead of
Change the firebaseMetaPath to "/apps"
In your filrebase real-time database create new node apps and create some element inside, just to create the node, later will be overwritten.
Now click on "apps" so you path in firebase is there.
In the Demo Data folder, you will find another folder All
Inside there is apps.json
Import that files in Firebase.
In config.js at the end, there is
Make it true
Now run your app