I formatted my sdxc 64Gb card to FAT32 on Windows 7 32bit computer using program FAT32program: http://www.ridgecrop.demon.co.uk/guiformat.htm and it works on Jolla without any problems. I have 3 folders on my sd card - Videos, Music and Photos. I did not had to do any mounting operations from command line - all content was recognized automatically by Sailfish programs within few minutes after installing sd card to Jolla (for sd card install / removal I do not power off Jolla).

*Only one thing bothers me - when I connect Jolla to my computer over usb I can only see my phone memory and not the sd card. For coping files to sd card I have to remove it from the phone and install it to my laptop (Lenovo X200s) sd card reader using the adapter. Would be more convinient to have direct access over usb.