CKAD Multicontainer lab not working

Hello,

Can you have a look, please ?

controlplane $ k get po -n elastic-stack
NAME READY STATUS RESTARTS AGE
app 0/1 ImagePullBackOff 0 2m38s
elastic-search 0/1 ContainerCreating 0 2m38s
kibana 0/1 ImageInspectError 0 2m37s