The SD card is for anyone with an autorouter account.
https://www.autorouter.aero/
It's free to join, and once you join, you can directly download and bring up charts on the MFD by entering your autorouter email and password on the "SD Card". This will only give you European charts.
The TBM also has the ability to download charts directly from the FAA, but with the release of the new navdata, there was a bug in that, so it won't work. A fix will be in the next update.
The next update will also have dedicated navigraph navdata.