I’m a Linux user on a Debian derivative. Gargoyle is great, and it might just be trying that is the easiest way to just get playing without worrying about it, especially if you’re not that used to working in the terminal.
There are a lot of reasons why you might have trouble saving, and most of them aren’t problems with Frotz itself. Check to see what the actual directory is that you’re trying to save into: is it write-protected? (Maybe this is the working directory, i.e. the directory that you were currently in when you invoked the
frotz command. Try specifying a full path, from the filesystem root, if you’re not sure.) Check,too, to make sure that you’re not using any unusual characters in the filename that you’re trying to save to.
But if you just want to get playing and not muck about with filesystem permissions and full pathways, it might be that just trying another interpreter is the quickest way to do so. Gargoyle is pretty good.