@dvaughanjones the number you refer to as a pin number is your case number, if i am understanding your question correctly.
Did you go to the FBI site, fill out a request for a criminal background check for a foreign visa, and then they e-mailed you a number within a short period of time - usually within an hour? If that is what you did, then that number you are referring to is your case number. You need that number to book your appointment for prints at the USPS. Make sure you are going to a USPS office that does direct digital prints for background checks…. many do not. You can get the list of which POs do this on the FBI website.
As to which application you need, you need the one for a foreign visa, the other is for firearms, I believe. it does not matter if it is a D7 visa or another type of visa, the background check is the same for any Visa.
Also, regarding payment: yes will also be paying for the record at that time as well.
all of this is based on the last time I requested a record for my PT visa. its possible they may have added an extra step to create a login and then you request the criminal record, and then once you have that, you go in and apply.
TIP: when you request the record, check the box that you want your record e-mailed… don’t wait for a paper copy, it will take forever, and add additional complexity to your process.
once you get your case number and then successfully send your fingerprints via the USPS office (or via hard copy on their form if you go to the local police station), they will email you a link that takes you to your record. This coule take as long as a week after they get your prints, as long as your prints are acceptable (i have difficult prints and have had them rejected multiple times, so i no longer use the digial method and have the police station use good old fashioned ink like the olden days).
anyway, once they send you the link for the record, you will go in and download/print it. it will be very underwhelming and will be something like one sentence that says you don't have a record - that is unless you happen to have some items on the record, but that is getting outside of my sphere if knowledge.
you heed to now get it apostilled… and it has to be sent to your lawyer or to AIMA. I use an apostille expediter that works with my digital record and then sends it directly to my lawyer in PT. I have written a very detailed step by step process on the whole criminal record and apostille process on another popular community board, but cannot link to that here. it you want the link, DM me.
the key is that the clock starts ticking on the validity of the record as soon as the FBI mails that link, so getting the entire apostille process and getting it translated and into AIMA’s hands before it expires in 90 days from the date you get the link to your record can be quite a scramble.
i hope this helps…. and forgive the plethora of typos - the site was hanging badly as I was typing making a mess of this post.