OK, so the zip file has 32 OTF files in a subfolder - awesome. But how does one install the .glyph files in the parent folder on, say, OS X?

I tried installing just the OTF files, but the extra glyphs are apparently not embedded in them and are inaccessible from (eg) Adobe Illustrator.

I can't find out how to embed the .glyphs (FiraSans_140521.glyphs and FiraSansItalic_140521.glyphs) into the OTF?