PIEE is the umbrella system DoD contractors use for invoicing, receiving reports, and related contract paperwork electronically. Wide Area Workflow, WAWF, is the piece inside it you will actually spend time in; submitting an invoice there and routing it for acceptance is usually how you get paid on a DoD contract. Setting up your account before you need to submit your first invoice saves you from a payment delay caused by paperwork rather than performance.

In a sentence

"Invoices shall be submitted electronically through PIEE using the Wide Area Workflow module." Get your PIEE and WAWF access sorted out during onboarding, not the week your first invoice is due, since account setup itself can take time.