TurboTax does not issue a 5 digit PIN to you----that five digit number is self-selected by the user. You make it up for yourself using any five digits you are likely to be able to remember--like maybe a childhood zip code, some of the digits from your birthday, etc etc. etc. If you requested a 6 digit PIN---it is issued by the IRS. You enter the PIN before you e-file.
If you have a 6 digit PIN issued to you by the IRS you need to enter it in order to e-file. Go to Federal>Other Tax Situations>Other Return Info>Identity Protection PIN and enter the six-digit PIN.