Mac should be able to open a zip, however, depending on version, OS or some other strange reason. Mac OS X has a built-in application to do this, Archive Utility, but apparently this does not work with every zip files. The Archive Utility error: “Unable to expand “myfiles.zip” into “Downloads”. (Error 2 – No such file or directory.).
The Mac is up-to-date running Mac OS X 10.7.3 and still running into this problem. There is several application to resolve this problem. E.g. StuffIt Expander is free on app store.
After installation right-click on the zip, Open with, Other. Select Applications and find StuffIt Expander and Open. The zip file expands it’s folder. Now the files are available.