Hi, I would do what Pitt is asking because of the GAP program you are applying to. Is the email related to the GAP? I would send your recommendors an email address to send their letters to if so. Upload your resume. Perhaps reach out to your rep. and explain. Maybe your recommendors can send their lor to the rep.
Good luck. My older D18 is currently at Pitt and got the GAP PA program, and my D22 just got the GAP for Pitt Law.