The link you have provided is no longer available. While learning and trying out Kubernetes for the first time I highly recommend using the official docs.

There you will find a detailed guide regarding Creating a single control-plane cluster with kubeadm. Note that:

To follow this guide, you need:

• One or more machines running a deb/rpm-compatible Linux OS; for example: Ubuntu or CentOS.
• 2 GiB or more of RAM per machine–any less leaves little room for your apps.
• At least 2 CPUs on the machine that you use as a control-plane node.
• Full network connectivity among all machines in the cluster. You can use either a public or a private network.

You also need to use a version of kubeadm that can deploy the version of Kubernetes that you want to use in your new cluster.

Kubernetes’ version and version skew support policy applies to kubeadm as well as to Kubernetes overall. Check that policy to learn about what versions of Kubernetes and kubeadm are supported. This page is written for Kubernetes v1.18.

The kubeadm tool’s overall feature state is General Availability (GA). Some sub-features are still under active development. The implementation of creating the cluster may change slightly as the tool evolves, but the overall implementation should be pretty stable.

If you encounter any issues, first try the troubleshooting steps.

Please let me know if that helped.