Usually settings are completed via sms when you first connect to the service, you click on the received link & it'll download the correct settings. I've never heard of asking for a PIN number to receive settings unless the phone itself has a security/pin code set. You could try this from vm's own help pages:
Every Virgin Mobile SIM card comes with a default PIN already set. So the first time you use the PIN, you’ll just need to enter 7890.
But it's a good idea to set up your own personal PIN for security. Have a look at our Mobile Guides to find out how.
Virginia/Doctor9fan. If I have helped please give me Kudos.