If you simply click on the link from the email, it will open the text into your browser window (depending on your browser settings -- some browsers may prompt you to download or save the file). If it open as text, then you can copy paste the text into a text editor and save the file from there (be sure to use a "plain text" editor, or to save it as plain text).
Otherwise, depending on your email application, you can right-click on the link in the email and choose "save link as" (or some similarly named menu item).
if you prefer using the command line, you can copy the link and use wget or curl. (but I'm guessing you won't be using this method)
If you are not getting a save link/target as option, then maybe you're using a tablet like an iPad or other mobile device where you don't have a filesystem and not allowed to save the file -- use a real computer.