Here Please consider flux-dev as ClusterName .

knts create cluster flux-dev --size SMALL

output :

Request Completed { status: true, cluster: "9dPIYtGvW8VPiZY6e0aU" }
{
  size: "SMALL",
  name: "flux-dev",
  createdDate: { _seconds: 1637837600, _nanoseconds: 936000000 },
  description: "flux-dev",
  features: {
    nfs_storage: { inputs: {}, requested: false, exec_status: false },
    ingress: { requested: true, inputs: {}, exec_status: false },
    cert_manager: { requested: false, inputs: {}, exec_status: false }
  },  
  version: "v1.19.12-k3s1"
}