Indeed, this cabinet is no longer up to date as required by the network operator for expansions. Not only that, but the spatial conditions are also crucial. From the front edge of the Z. cabinet, there must be no fixed installations 1.2m rearwards (clearance at the back). If this is given, there are good chances to upgrade/convert this cabinet so that the network operator gives their approval. The upper connection space above the meter should be 300 mm according to the new standard instead of 150 mm as here, but it will still be accepted. Otherwise, it must be replaced or newly installed at another suitable location. Then the “old” one can/could remain in operation as a subdistribution without a meter.
The matching covers for this cabinet are still available. The lower right 3-field cover must be replaced by one with one row and one with two rows. In addition, the 2 nipples for the now additional fastenings for the covers. With that, you have conjured the required APZ field. If cables are now also introduced from below in the right area into the Z. cabinet, a PVC plate/shielding over the entire surface is sufficient for this. …… and one more thing, SLS 50A wiring of the meter must necessarily be done with 16 square cables, without twisting and bending.
Your electrician authorized by the network operator knows the rules of the game.