versions of roblox studio from late 2013 can open binary rbxl files and resave them as the file type needed (which is formatted as xml)
one of the ones i know that can is the one from october 17th 2013
https://github.com/BakonBot/legacy-place-converter
first u need to open ur map in normal roblox studio
next save the map as a .rbxlx file
then open the converter and put that file in there
wait for it to convert
then upload the new .rbxl file that the converter put on ur pc to austiblox
hope this works bc it did for me