They are claiming the Trump Organization payments to Daniels, via Cohen, were a campaign contribution and thus failure to report them was a FECA violation. This is despite Trump never being charged for a FECA violation, let alone convicted.
But a campaign can’t legally spend money for hush payments. The money never went through the campaign at all. Cohen charged for legal expenses and the Trump Organization paid him for his legal work. It had nothing to do with Trump for President 2016.