can anyone help:

I'm on my apple mac using OS 10.5.8 [core 2 duo]

I downloaded
the zip file for clients from github

when I click on the zip file it opens all the zipped files except the one I need
Maxcoin-OSX64.zip

I get error:
Unable to unarchive Maxcoin-OSX64.zip into clients-master
Error 1 operation not permitted

Any suggestions?

thx