Error loading Namespaces. Unauthorized: Verify you have access to the Kubernetes cluster

You will need to add your IAM role/user to your cluster's aws-auth config map

Basic steps to follow taken from

kubectl edit -n kube-system configmap/aws-auth
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
apiVersion: v1
  mapRoles: |
    - rolearn: <arn:aws:iam::111122223333:role/eksctl-my-cluster-nodegroup-standard-wo-NodeInstanceRole-1WP3NUE3O6UCF>
      username: <system:node:{{EC2PrivateDNSName}}>
        - <system:bootstrappers>
        - <system:nodes>
  mapUsers: |
    - userarn: <arn:aws:iam::111122223333:user/admin>
      username: <admin>
        - <system:masters>
    - userarn: <arn:aws:iam::111122223333:user/ops-user>
      username: <ops-user>
        - <system:masters>