Presuming you're using a PC, create two folders on your desktop. Label one Old Sat Nav, and one New Sat Nav. Copy the content of the SD drive to the old folder before you start so that you have a back up if needed. Download your choice of new file from the VW Sat nav update page, for the year of your car, download to your computer then unzip/extract the content to the New Sat Nav folder. Go to your SD card, in your card reader/ file manager and right click it and choose format this drive. Select the FAT 32 format option and click ok. When the SD card is formatted, copy the unzipped map download to the SD card. Insert into the SD slot in the glove box, go to the Sat Nav screen, hit settings and update the Sat Nav software. Hope this helps. My version shows 5NA919866AS 1520 ECE1 2021.