The report does not link Manning to Delta-2, but Sly and Robertson name multiple football players as customers, including Green Bay Packers linebacker Mike Neal. Neal, Sly says, connected him with multiple teammates, including defensive end Julius Peppers.
Full story here: http://www.huffingtonpost.com/entry/peyton-manning-human-growth-hormone_567f16e4e4b0b958f6599440?ncid=tweetlnkushpmg00000067
ETA: The report mentions Matthews as well:
Sly also says that he provided Clay Matthews, Green Bay’s Pro Bowl linebacker, with the prescription painkiller Percocet to help him deal with pain before at least one game. He also brags in one undercover video that Matthews texted him in an attempt to obtain Toradol, a powerful painkiller that is banned in many countries but not in the United States.