You can't use a beatmap that isn't yours, the only choice you have is to map it by going to the beatmap file, drag the .mp3 file to where it is "drop the .mp3 file". and map it from there. Your welcome. (If you need help looking for the beatmap file, Right-Click osu!, Click "Open File Location" and look for the folders called "Songs" and after that look for the folder for the beatmap you are trying to recreate/publish. Oh and, most of what I said had been mentioned in the pastebin link above just pointing that out.)