Western Union will usually allow you 2 or 3 transfers without filling out the verification form. The form is actually a PagoFacil form, but it does go to AFIP in the end, I am pretty sure. If you want to regularly use WU, you pretty much need to fill out the form. After your first transfer, WU will email you a link to this form. It wants info on your ID, address, and what the transfer is used for.
https://www.westernunion.com/ar/en/how-to-register.html