Some premium or custom WordPress plugins may require you to install them through FTP.
- Connect to your hosting with FTP.
 - Navigate to the directory containing your WordPress site.
 - Upload your plugin to the /wp-content/plugins directory.
 - If your plugin is zipped, you will need to unzip it. (cPanel / Plesk / Web Hosting) 
Note: If you do not have a way to unzip the file on the server, you will have to unzip the file locally and then upload the unzipped directory of files.
 - Your plugin should now display on the Plugins page within your WordPress Dashboard.
 
Next steps
More info