What does it mean if it says the Service Provider is not set up?

If an appointment says that the service provider is not set up it means that the service provider is either not checked off as as Active or they do not have a Subscription 

You can add a subscription to a service provider from the Service Providers tab by clicking on "Subscribe" or "resubscribe".

You can activate the service provider by editing their account in the Service Providers tab and checking the "Send Messages?" checkbox.