There are multiple ways you can install a plugin, so the Disqus Conditional Load. Two of the most common ways are doing it via the WordPress dashboard, and via FTP.
Follow these steps to install the plugin via FTP. To install it via FTP you will need direct access to your web host’s file server. Make sure you have a file transfer program (for example Filezilla) available, and have the correct rights from your hosting provider.
On your local machine unzip the plugin zip file which you have downloaded already.
Login to your site using FTP or SFTP.
Upload the extracted folder to the
wp-content/plugins/directory on your site.
Go to the plugins list page and activate the plugin.