You should be able to update the maps from the system page, there are details on how to do this in the navigation manual - however my new MG ZS EV (with old maps) navigation device doesn't have an SD card, and after a lot of trial and failure I found that to do the first map update you need a usb device formatted with specific software to write the "fingerprint file" (i.e. the copy of the data on your head unit which the web application needs to configure the updated maps). The dealership should have provided that file on a usb with the car, but they didn't. So I'm off back to the service department to get them to sort it out for my first update, then I'll either do the updates myself using the usb, or get it done as part of servicing.
I will update this forum with the results.