problem in category page

[eimonAAptech]

 db.collection(departmentAdapter.items[position].departmentName).get()
            .addOnSuccessListener { documents ->

                for (document in documents) {
                    val i = document.toObject(Furniture::class.java)
                    list.add(i)
                }

can't fetch data from FirebaseFirestore showing "com.google.firebase.firestore.FirebaseFirestoreException: PERMISSION_DENIED: Missing or insufficient permissions." this error on clicking on category. can't test this app.