First, double check with the information below (including the link showing photos) to make sure. But, if your license doesn't have this document number on it, then you can skip the entire section. You should be able to hit continue without actually entering any of the license information (leave it all blank, not just the document number section). Your return will still be processed without it as the IRS does not require the license number and neither does NY, but they are asking for it more of an identity protection measure (some states like Alabama and Illinois are requiring it).
The document number is an 8 or 10 digit alphanumeric number found either on the back of the license or lower right hand corner (depending on the year of your license). It is not the same as the drivers license number. I have included a link to the NY authority that displays images below.