Connect grafana oncall with grafana through plugin

I installed grafana oncall following this link and when I open localhost:8080 in browser it shows “OK”.
Then I open grafana and added the grafana oncall plugin it gives me the following error when I click in connect:

Can someone help me on what should I do?l

Ok, on my ubuntu machine where I have installed docker I just needed to update the repositories

  • sudo apt-get update
  • sudo apt-get upgrade