Sorry, i must be missing something obvious. Going to the 'File>Open' menu i only see the files on my computer, not the ones on the SD card.
Going to 'Window>File Manager' i see the files on my SD card (including index.axb), but neither an 'open' nor a 'download' option (there is 'upload', which i guess would allow me to copy a file from my computer to the SD card, but...)
Going to 'File>New patch bank', i have an option 'Upload bank table', which, i guess, saves the axb file to the SD card, but no option to save it to my local machine, so i wouldn't know how to do what you suggest ("i save the axb on my computer somewhere").
I have version 1.0.12, running on a MacbookAir 10.12.6.