You should never use localhost in a url as that will always point the that particular machines IIS. You need to use the Public url to your arcgis server. Normally the web adaptor can be used to to redirect the url to your ArcGIS Server services if your ArcGIS Server and your web server are not on the same machine. Not sure about to comment on waiting for a licence for the web adaptor. If you have a license for ArcGIS Server then you have a license for a web adaptor.