It definitely sounds like you are doing a form 1 and not a form 4. A form 1 is an application for a non licensed person or entity to make a NFA item. A Form 4 is an application to transfer a NFA item from a licensed dealer to a non licensed person or entity. In Short, a form 1 is for you to make your own SBR and a Form 4 is if you are buying that SBR from a dealer.
You can do your own fingerprints which may be easier. A lot of people used to go to their local PD or Sheriff, but with COVID, a lot of these extra services have been suspended. There are also private fingerprinting services, but they charge a lot more and still may not be open. If you go the "roll your own" route, you can get free fingerprint cards from the ATF, although I hear they are running a little slow these days. Depending on where you live, I have a bunch of extra ATF fingerprint cards that I can spare. Also, when submitted multiple eform 1 applications, you only need 1 pair of fingerprint cards for the multiple forms. The ATF has confirmed that you can mail 1 pair of cards with the multiple cover sheets and they will all be processed.
If you are submitting a eform 1, I would just use a phone app to take the picture and upload it to the eforms site.
Also, if you are mailing in a paper form 1 be prepared to wait for months. I would definitely suggest using the eforms system as that is still taking approx 30 days.