Stonk, can you confirm which product we are talking about? Note that MCL2A, MCL2AV, MCL X-tra speaker kit and MCL X-tra active speaker kit are all different products!
As far as I know all of them are supposed to connect to the Beomaster via an MCL cable - and in all of them(?) it is connected to a screw terminal strip inside the box, so there is no connector for it. So you need an MCL cable with one end open for the MCL box, and with two 3-pin speaker DINs on the other end for the Beomaster.
The 7-pin DIN sounds like it is the connector for the IR transceiver (or a Beovision AUX, depending on the product).
(on the membership issue, have you tried logging out & back in already?)