Terrain data in matek f405-wmn

Is it possible to use terrain data with the Mateksys F405-WMN?
As per the spec it has 16MB of datalog flash. And as per the ardu docs from here:

16MB Flash for data logging, WTE has microSD card reader instead of flash chip

Which makes me think that the flash can be used as a “substitute” for an SD card.
Unable to upload anything via mavftp, cannot create directories.

The only seemingly related post on the forums is this one - without an answer, though…

Many thanks in advance.