On macOS, you should simply be able to double click on the zipped file to unzip/extract, except with zip password protected files.

If you get an error message in a small window pop-up:

• Unable to unarchive "filename.zip" into Desktop (Error 1 - Operation not permitted.) "Decompression Failed" or...

• Unable to expand "filename.zip" into "Desktop". (Error 1 - Operation not permitted.) "Decompression Failed"

Then follow the steps below for alternative unzipping processes. 

First, double check to make sure the ZIP file has fully downloaded. If the file size has fully downloaded then use unzip in Terminal to overcome this error message:

One solution is to use Terminal, a program included with all versions of Mac OS X. It is located in the Utilities folder within the Applications folder. When launched, it provides a line interface to control the underpinnings of the UNIX based operating system.

• 1) Open Terminal. You can use the Mac search at the top right and start typing Terminal. It will appear, click on it to open the program.

• 2) Type “unzip” and a space, then drag/drop the zip file into the Terminal window. 

• 3) Press Enter and the zip file will be unzipped, storing all files on your computer.
  
  Your unzipped files will go to your user account folder which you can easily access using Finder.