Don't use a Mac is one... but if you do use one you need to pay attention to the section from the VW pdf:
》》
Unzipping map material
ATTENTION
If the map update is performed using the Apple® OS X operating system you may find that
Discover Pro does not recognise the map material or displays it incorrectly. This is due to a
lack of compatibility between the “7 zip” program and the OS-X operating system. In addition,
the OS-X operating system has a tendency to create hidden additional files on external data
media. We therefore recommend that OS X users use the “Keka” unzipping program. We also
recommend using the “CleanMyDrive” program to remove any hidden files.
《《
https://webspecial.volkswagen.de/vwinfotainment/dam/jcr:c08aab64-ee73-4082-86a6-0fa82362282a/Discover Pro June_2019_EN.pdf
Keka and CleanMyDrive on the SD card.
For a PC only use 7Zip to unpack. Drag and drop the contents from the archive to the HD, then copy to a blank 32gb SD card formatted to Fat. Deviate at your own risk. Some say can use this, that and the other but that's not the VW advice. Other unzip programs can mess up the unzipping process. The upload to the car uses a signature check so any stray bites in there and the import is abandoned.