Cannot create directory '/mnt/cluster_storage'

I tried to run the XGBoost training example as described here on a Ray Cluster created using ray-ml:2.7.0-py310-cpu on GKE.

When I submit the job by running the script in the link, I get PermissionError: [Errno 13] Cannot create directory '/mnt/cluster_storage'. Detail: [errno 13] Permission denied during the training process. Attaching the Traceback:

Traceback (most recent call last):
  File "/home/ray/ray/release/air_tests/air_benchmarks/workloads/xgboost_benchmark.py", line 57, in run
    super(MyProcess, self).run()
  File "/home/ray/anaconda3/lib/python3.10/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "/home/ray/ray/release/air_tests/air_benchmarks/workloads/xgboost_benchmark.py", line 102, in run_xgboost_training
    result = trainer.fit()
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/train/base_trainer.py", line 653, in fit
    result_grid = tuner.fit()
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/tune/tuner.py", line 372, in fit
    return self._local_tuner.fit()
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/tune/impl/tuner_internal.py", line 579, in fit
    analysis = self._fit_internal(trainable, param_space)
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/tune/impl/tuner_internal.py", line 699, in _fit_internal
    analysis = run(
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/tune/tune.py", line 851, in run
    experiments[i] = Experiment(
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/tune/experiment/experiment.py", line 204, in __init__
    self.storage = StorageContext(
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/train/_internal/storage.py", line 474, in __init__
    self._create_validation_file()
  File "/home/ray/anaconda3/lib/python3.10/site-packages/ray/train/_internal/storage.py", line 498, in _create_validation_file
    self.storage_filesystem.create_dir(self.experiment_fs_path)
  File "pyarrow/_fs.pyx", line 593, in pyarrow._fs.FileSystem.create_dir
  File "pyarrow/error.pxi", line 113, in pyarrow.lib.check_status
PermissionError: [Errno 13] Cannot create directory '/mnt/cluster_storage'. Detail: [errno 13] Permission denied

Ray Cluster yaml

apiVersion: ray.io/v1alpha1
kind: RayCluster
metadata:
  labels:
    controller-tools.k8s.io: "1.0"
  name: raycluster-autoscaler
spec:
  rayVersion: '2.7.0'
  enableInTreeAutoscaling: true
  autoscalerOptions:
    upscalingMode: Default
    imagePullPolicy: IfNotPresent
    securityContext: {}
    env: []
    envFrom: []
    resources:
      limits:
        cpu: "500m"
        memory: "512Mi"
      requests:
        cpu: "500m"
        memory: "512Mi"
  headGroupSpec:
    rayStartParams:
      dashboard-host: '0.0.0.0'
    #pod template
    template:
      spec:
        nodeSelector:
          cloud.google.com/gke-nodepool: default-pool
        containers:
        # The Ray head container
        - name: ray-head
          image: rayproject/ray-ml:2.7.0-py310-cpu
          ports:
          - containerPort: 6379
            name: gcs
          - containerPort: 8265
            name: dashboard
          - containerPort: 10001
            name: client
          lifecycle:
            preStop:
              exec:
                command: ["/bin/sh","-c","ray stop"]
          resources:
            limits:
              cpu: "3"
              memory: "12G"
            requests:
              cpu: "2"
              memory: "11G"
  workerGroupSpecs:
  - replicas: 1
    minReplicas: 0
    maxReplicas: 10
    groupName: small-group
    rayStartParams:
      resources: '"{\"small_jobs\": 1}"'
    #pod template
    template:
      spec:
        nodeSelector:
          cloud.google.com/gke-nodepool: small-pool
        containers:
        - name: ray-worker
          image: rayproject/ray-ml:2.7.0-py310-cpu
          lifecycle:
            preStop:
              exec:
                command: ["/bin/sh","-c","ray stop"]
          resources:
            limits:
              cpu: "3"
              memory: "12G"
            requests:
              cpu: "3"
              memory: "12G"
  - replicas: 1
    minReplicas: 0
    maxReplicas: 10
    groupName: large-group
    rayStartParams:
      resources: '"{\"large_jobs\": 1}"'
    #pod template
    template:
      spec:
        nodeSelector:
          cloud.google.com/gke-nodepool: large-pool
        containers:
        - name: ray-worker
          image: rayproject/ray-ml:2.7.0-py310-cpu
          lifecycle:
            preStop:
              exec:
                command: ["/bin/sh","-c","ray stop"]
          resources:
            limits:
              cpu: "6"
              memory: "25G"
            requests:
              cpu: "6"
              memory: "25G"