FYI, XLSX files ARE zipped. If you look at it in an editor or hex viewer, the first two characters are PK, which indicates it's a ZIP file (from PKZIP, the forerunner of modern ZIP, where PK stands for Phil Katz, who invented it).
If you run unzip (or pkunzip, etc.) on the file, it creates some directories that are full of XML files and RELS files (MS Office 2007+ relationship files). Any module working with an XLSX file would need to include something from the Archive::ZIP family.
That said, I don't work on a Mac, but I would have assumed Spreadsheet::XLSX would have installed Archive::Zip::Archive as a dependency. Maybe the OP should try installing it manually.