First of all, you need to login Twitter: https://apps.twitter.com/

Secondly Get the zip file from https://wordpress.org/plugins/teg-twitter-api/

After that:

Installing your plugin is not a difficult task. You just need to follow following steps below.

1. Install the Accordion for WordPress from the WordPress.org. Simply go to Plugins >Add New in the WordPress Dashboard.
2. Search for the TEG Twitter API
3. Select the TEG Twitter API  plugin and install
4. Activate after installation

Additionally, if you are using FTP to transfer your files to your server. Get the zip file from https://wordpress.org/plugins/teg-twitter-api/

click the download button. Then just unzip the plugin and upload directoryteg-twitter-api to your directory/wp-content/plugins/.