My assumption would be that you did not install your custom nodes correctly. Looks, for example like you are running n8n in two different ways. One time locally installed via npm and one time via Docker. If you run n8n in Docker the custom nodes can not show up (unless you really know what you are doing and you configured everything accordingly).
So my suggestion would be to stay with the on your host npm installed version of n8n + nodes installed locally as in the already previously shared video. If you follow that video step by step without diverging, the node should show up fine.