There are two W3Speedster installation options: Automatic or Manual.
Download W3Speedster
Once you have bought W3Speedster, you can download the zip file from your W3Speedster account page. or to use free version you can download it from plugins option in your Dashboard
Disable Automatic Un-Zipping in Safari
If you want to use the Automatic Installation method for W3Speedster, ie. installing the plugin through your WordPress dashboard, you need to start with the zip file of the plugin. If you use Safari, it might be unzipping it for you which causes confusion.
Go to Safari > Preferences and un-check the box labeled ‘Open “safe” files after downloading’:
Now you can download the zip file normally and proceed with the installation.
Automatic Installation
Automatic installation is the easiest way to install W3Speedster.
To do it, log in to your WordPress admin panel and go to Plugin > Add New and click on Upload Plugin. Or just search for w3speedster and click on install.
Select the zip file and click on Install Now. After clicking that link, you will be asked if you are sure you want to install the plugin. Click yes and WordPress will automatically complete the installation process.
Once it’s activated, simply go to the W3speedster panel.
Manual Installation
The manual installation involves uploading all the files to your web server through FTP software. Unzip the archive, then upload the ‘w3speedster’ folder to “wp content/plugins” directory. Finally activate the plugin through your WordPress admin.
Once it’s activated, simply go to the W3speedster panel.