It's seems like a database error. Your database is set to use caching_sha2_password as an authentication plugin. You need to change it from your mysql config.
In your mysql configuration file, you may want to change default_authentication_plugin parameter:
[mysqld]
default_authentication_plugin=mysql_native_password
You need to restart mysql server to make this change active.
Also you may change it by user with the following sql statement:
ALTER USER 'user'@'host' IDENTIFIED WITH mysql_native_password BY 'password';
If you do not depend on mysql you can change database engine to sqlite and run the project. If there is no coding error, it should run smoothly. After solving mysql issue you can switch back to mysql backend.