I'm having problems signing in as well. I'm pretty sure I found the correct # in the subject line of an 7/7/15 email from Receipt.Application@epa.gov, because it matches the description below taken from the scgcorp.com website, but it still didn't work.
"During that initial application process, you will be able to use your temporary PPRD (Policy, Planning and Review Division) number to access your Fellowship Information Inventory webpage. The PPRD number has 9 characters with no spaces. It starts with a capital alphabetical character, followed by two numbers, then another capital alphabetical character, then followed by five numbers (e.g. F50C12345)."