I only know from my own experience with Renault R-Link:
I copied various online downloads onto an SD card, but the navigation software (TomTom map) didn't recognize them.
I bought an SD card with the latest map on eBay for €25, and it was recognized perfectly 👍
However, it didn't work in an acquaintance's R-Link system because the R-Link writes an ID file back onto the SD card—meaning it's only recognized by my Renault...
In my opinion, it’s likely the same story with MAN...