Error establishing a database connection (Set-up locally)

This is my first time working on Wordpress and accessing site locally.

The Wordpress site is on the github and I tried to pull the codes from there and accessing site already to my local machine but when I tried to access the site locally it always saying

Error establishing a database connection

I already checked DB_NAME, DB_USER and DB_PASSWORD inside wp-config.php and already created a database inside phpMyadmin locally and imported the DB from github but still the problem is there. Is there anything wrong with my configurations or steps that I am doing?

Thanks in advance for the help.