problem accessing Ambari on HDP 2.1 Saandbox using VirtualBox VM

Problem accessing Ambari on the VirtualBox VM using HDP 2.1

I downloaded the HDP 2.1 Sandbox for VirtualBox. I was able to start the VM and access it using this URL:

http://127.0.0.1:8888/

I logged onto the VM and I ran the following cmmands at the command line:
> ambari-server setup
….
> ambari-server start

The reply was the Ambari server was already running.
When I tried to access the Ambari server using this URL

http://127.0.0.1:8080/

I got a HTTP 403.11 error.