How to resolve the permission errors for MySQL server?

I am trying to work on this project. https://github.com/thiagogomesverissimo/symfony_traditional_login Following the instructions. But when I was executing

php bin/console doctrine:migrations:migrate

Then I get the following errors:

In AbstractMySQLDriver.php line 112:

An exception occurred in driver: SQLSTATE[HY000] [1045] Access 
denied for user 'master'@'localhost' (using password: YES)                               

In PDOConnection.php line 50:

SQLSTATE[HY000] [1045] Access denied for user 
'master'@'localhost'(using 
password: YES)                                                                

In PDOConnection.php line 46:

SQLSTATE[HY000] [1045] Access denied for user 'master'@'localhost' 
(using password: YES)

I did try to edit the mysql url in the env file like below:

https://github.com/thiagogomesverissimo/symfony_traditional_login/blob/master/.env.dist

DATABASE_URL=mysql://db_username:db_password@127.0.0.1:3306/db_mydbname

Another try was:

DATABASE_URL=mysql://root:root@localhost/mydbname

I am just replacing the username, password, and mydbname with my information. But still getting the same errors. Any help would be highly appreciated.