I figured it out This is important for people to know about Macs and compression. By default, Safari automatically expands compressed files. In order to import the file, I had to re-compress the file. Apparently, whatever approach Mac uses to compress, it creates a file that openLCA refuses to import.
So...go into the preferences for safari, click on the General tab and UNCHECK the "Open safe files automatically" option.
On downloading the methods file, it remains compressed and apparently it can be read properly by openLCA