You can get these above credentials from your Developer Account. If you already have a developer account, simply just go to the “Keys and tokens” section from the Apps page. Then you will find the “Consumer Secret Key“.
Reference
You can find out how to create a Twitter App in the following article”
https://jkdevstudio.com/documentations/maniel-multi-concept-blog-magazine-wordpress-theme/tips-tricks/twitter-api/how-to-create-a-twitter-app/