k8s installation error

While doing step - Lab 2.2. Deploy a New Cluster

6. When the script is done the minion node is ready to join the cluster. The
   kubeadm join statement can be found near the end of the
   kubeadm init output on the master node. It should also be in the file
   master.out as well. Your nodes will use a different IP address and hashes than the example below.
   You’ll need to pre-pend sudo to run the script copied from the master node.
   Also note that some non-Linux operating systems and tools insert extra characters when
   multi-line samples are copied and pasted. Copying one line at a time solves this issue.

I am getting the below error. Please help me on this error.

student@master:~$ sudo kubeadm join 10.2.0.2:6443 --token o8t2te.4ks1kqu0roz04nmj --discovery-token-ca-cert-hash sha256:b7c5b5ed39b16b35e4b26dd8f6fc23e244453133a0dcce408cd5960a12ad5ffe
[preflight] Running pre-flight checks
[WARNING Service-Docker]: docker service is not enabled, please run 'systemctl enable docker.service'
[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
error execution phase preflight: [preflight] Some fatal errors occurred:
[ERROR DirAvailable--etc-kubernetes-manifests]: /etc/kubernetes/manifests is not empty
[ERROR FileAvailable--etc-kubernetes-kubelet.conf]: /etc/kubernetes/kubelet.conf already exists
[ERROR Port-10250]: Port 10250 is in use
[ERROR FileAvailable--etc-kubernetes-pki-ca.crt]: /etc/kubernetes/pki/ca.crt already exists
[preflight] If you know what you are doing, you can make a check non-fatal with --ignore-preflight-errors=...
To see the stack trace of this error execute with --v=5 or higher