I did not go to the embassy, but printed the same form from the FBI web site, however, when I wen to the Registro Nacional de Reincidencia they already had them printed on heavy paper. The fingerprinting took only a few minutes. To answer to your question, yes you have to send the actual fingerprint card to the FBI so they can use your prints to search their database. To do that you have to 1) create the request online through their web site
https://www.edo.cjis.gov/#/; while doing that you have to specify that the fingerprints will be mailed separately. At the end they will send you an email, which you have to print. 2) Send the fingerprint card, together with the email you received, so they are able to reconcile your electronic request with the paper fingerprint form. While creating the request online, specify that you need the PDF form of the rap sheet, as this is enough and you don't need the actual paper document (thus solving the problem of mail coming to Argentina taking ages). After that, you need to have the rap sheet authenticated by the Department of State, but here I cannot be of any help, as in my case that was taken care by my lawyer, so I assume you can request the service of Monument Visa, as suggested by gringoexpress.
Good luck.
