There is your answer. If you have an index.php in the directory of a website, it works. If you don’t have an index.php, it doesn’t work.
Directory listing is disabled by default on our hosting, so you’ll see a 403 Forbidden error if you try to open a directory without an index file. You can read more about that here: Redirected to InfinityFree 403 Forbidden page
To fix macedoniansweregreeks.com, simply upload a index.php file to the htdocs directory of the domain.