[onona]

Trump’s strategy is to stand firm—to reject the idea that the GSA, FBI, or DOJ have any right to dictate the terms under which he assumes office. His limited MOU with the GSA

I got two out of the four acronyms (abbreviations more like it)

[RainMan]

GSA = General Services Administration = Primary Contracting Administrators of the government.
FBI = Federal Bureau of Investigation
DOJ = Department of Justice
MOU = Memorandum of Understanding

The transition bureaucrats were trying to force Trump to agree to their terms. Trump said no. He finally agreed to a limited scope of authority for the bureaucrats to help. That is what is referred to as the MOU.