If you are unable to use any of the methods due to internet connectivity and file permission issues, then you can use this method-

1. Download the plugin by clicking on this link. A ZIP file will be downloaded.
2. Unzip the file.
3. Launch your favorite FTP client. Such as FileZilla, FireFTP, CyberDuck, etc. If you are a more advanced user, then you can use SSH too.
4. Upload the folder to wp-content/plugins/
5. Log in to your WordPress dashboard.
6. Navigate to Plugins -> Installed
7. Activate the plugin