Helm install:

helm repo add portainer https://portainer.github.io/k8s/
helm repo update

helm install --create-namespace -n portainer portainer portainer/portainer

Then create the service:

kubectl apply -f portainer-service.yaml

(Optional) Restart Portainer if it timed out before setting up initial account:

kubectl get deployments -n portainer
kubectl scale --replicas=0 deployment portainer -n portainer
kubectl get deployments -n portainer
kubectl scale --replicas=1 deployment portainer -n portainer

Set up admin access by going to the URL referenced in the Service.