I sent a .zip file to a friend with an iMac but he can't open it. It was created using PKZip on a Windows 7 PC, and it's Password protected. He's pretty technically inept so is there anything he needs to do to be able to access this file please?
macOS has built-in support for password protected Zip files, but if he encounters problems have him get The Unarchiver. It also does other kinds of file types.