TurboTax requires the 5-digit PIN that the IRS provides. If you saw a reference to a 6-digit PIN then you were likely in a wrong section dealing with identity theft.
The 6-digit IP PIN (identity protection PIN) is only for those taxpayers who were mailed a letter from the IRS with the IP PIN enclosed. Those taxpayers have been subject to identity theft. If you are not a victim of ID theft and did not receive the letter from the IRS, then you do not have a 6-digit PIN and don't need to be in that section of TurboTax.
You are trying to enter your 6-digit PIN (the Identity Protection PIN) in the wrong place. It is NOT entered in the efiling section. The 5-digit PIN in the efile section is something different that people use to sign their returns for efiling.
Here is where you enter your 6-digit IP PIN (from the letter the IRS mailed you).
From the FEDERAL TAXES tab. Click the subtab "Other Tax Situations." Scroll down to "Other Return Info" Find subtopic "Identity Protection PIN", and click START (or Update).