after downloading instead of extracting the whole folder straight to skins,extract it to another place on your hardrive then go to it open it up and copy and paste just the stelko x1 folder to user documents/si/fm11/skins
i had this problem when i first tried it and i hav normal pc it worked after that
when you download it it has 4 diffrent styles of stelko in 4 diffrent folders,just choose and put 1 of the folders in skins
i reckon this is your problem folks it should work on mac