How to use unzipper.php file
When the unzipper.php file is on your computer, say on the desktop, then:

Upload a zip file (for example a zipped copy of WordPress) into the desired directory

Upload the file ‘unzipper.php’ to the server into the same directory with the .zip file. Make sure .zip file and folder are writable.

As soon as you finish, open your site in the browser and add the file name ‘unzipper.php’ to the URL. It should look like this: yourwebsite.com/unzipper.php:

Then, in the page that shows,
Select the .zip file you need to unzip. You will also see the following options: “Delete .zip after extraction?” and “Delete Unzipper Script? (Uncheck this box if you have more files to unzip!)”

After you have selected all needed options click on Unzip! button.

You can then delete unzipper.php from the directory. You can also remove the left-over zipped file now that it has been unzipped.