this is what you need to buy, and yes it plugs into the quad lock connector, be careful with buying Non VAG parts, the green adapter can be to big for the quad lock.
https://www.ebay.co.uk/itm/304147839733?epid=648652162&hash=item46d09fbaf5:g:5wkAAOSwOghfn1A5
And yes it goes behind the grille in the courtesey light and clips into place ( Piccys below). It's pretty straight forward, runs from the radio behind the top glove box, then up the L/H A pillar and across to the light.
Obviously you want the radio removed......
Then you only need to remove the courtesey lamp assy (remove plastic lens), undo 2 screws, let the light dangle,
L/H A pillar trim just "pulls off towards the opposite side, so like "across the dash"
Top glove box, just open it, there is 2 screws on upper surface, remove those and it then pulls straight out.
Finally remove the fixing that holds the hinged part of the L/H sun visor, this enables a "little" flex in the roof panel when feeding the wire to the light (open cap, remove screw)
Then it's a case of feeding from the radio, then along behind topo glove box, up the A pillar (secure to exisiting wiring with cable ties or tape) and across above roof trim.
To get the wiring from the top of the A pillar to the courtesey light hole, using a "fishing" rod like a coat hanger or stiff piece of wire or similar pushed back from the courtesey light hole, tape your mic / wiring to it and use that to pull the wiring through.
To work "well", the microphone is best placed at this height, it is very straight forward and works very well.