Unscrew the two screws (shown below) that secure the controller board to the machine bracket and lift out the board
Disconnect the white connector, shown in red circle below, from the board:
In its place, connect the white connector (with the 4 wires in it) from the reader cable harness:
Connect the machine connector you disconnected two steps ago into the reader cable harness other white connector (the harness acts like a splitter)

Connect the “Busy signal” connector to the board:

Connect the spade connectors from the cable harness to the female spades in the machine