The normal installation methods for WordPress plugins work:

1. Go to the Plugins->Installed plugins screen in WordPress Admin. Click on Add New. Search for MSTW CSV Exporter. Install and activate it.
2. Download the plugin (.zip file) from WordPress.org. Go to the Plugins->Installed plugins screen in WordPress Admin. Click on Add New. Click on the Upload link. Find the downloaded .zip file on your computer. Install and activate it.
3. Download the plugin (.zip file) from WordPress.org. Unzip the file. Upload the extracted plugin folder to your website’s wp-content/plugins directory using an FTP client or your hosting provider’s file manager app. Activate it on the Plugins->Installed plugins screen in WordPress Admin.