To fit a microswitch credit mech you need change the door for a coin controls one
You could just fit a standard extra button on the cab with a microswitch direct to 0v and your credit wire on the game board (that’s then freeplay if it’s home use only?)
This door requires a Mars 126 type validator plus an associated mars credit pcb to output pulses to a game board
ALSO THE DOOR MOUNT PLATE APPEARS TO BE MISSING THE TWO ORANGE MECH HOLD/RELEASE CLIPS , which screw on to the clear plastic…
NOTE ! The mech needs to be front entry front reject ( as top entry bottom reject and variants are available) programmed to the coins you desire to use
When fitting these the supply voltage is just one 12v dc +. & one Ground 0v and one output wire to the credit wire in the loom .. (usually pin 16 on component side of a jamma type pcb)
if in doubt which that one is refer to a jamma edge connect diagram or put up a photo of your existing wiring at the game board.