Flutter & Firebase App Tutorial #17 Write failed at brews/ : Status{code=PERMISSION_DENIED, description=Missing or insufficient permissions., cause=null}

When I register a new user this error shows up:

`W/Firestore(22296): (22.1.1) [Firestore]: Write failed at brews/...: Status{code=PERMISSION_DENIED, description=Missing or insufficient permissions., cause=null}`

My Firestore rules:

```
service cloud.firestore {
match /databases/{database}/documents {
match /{document=**} {
allow read, update, write: if request.auth != null;
}
}
}
```

The brews collection doesn't get created. What am I doing wrong?