Need support with Kubernetes Tutorial Video


important infor in advance:
I am an absolute beginner in the subject of Kubernetes!
However, since I am interested in the topic, I watched the following video:

So far I understood everything…but the problem is that when I run the command in min 1.04.27…

By executing the command

kubectl get pod → in the Video, there is no pod running
Well in my case, there is a pod running called hellominikube (i guess thats the pod from the vm)

But the main issue I have is, that iam not able to execute the command:

kubectl apply -f mongo-config.yaml

Iam in the same folder, where the datas are stored but if i use powershell, i get following error message:

error: no objects passed to apply

How can I fix the problem?