Find a bug in Java Spring project

Kindly provide a FINAL FIXED PRICE for resolving the bug after conducting a thorough investigation. Any attempt to renegotiate or increase the price will not be accepted.

I am working on a Java Spring project and I've encountered a bug that requires resolution. I am seeking assistance from a skilled developer to fix this issue.

GitHub repo: https://github.com/JShipov/java-test

NOTE: Please refrain from extensive testing of the email functionality, as there are currently usage limits in place.

Project Overview:
The project is a full-stack freelancer search platform.

Technical Details:

Front-end: React
Back-end: Java (using Spring, Maven)
Database: mariaDB
Current Functionality Implemented:

A user can register by clicking the "Sign Up" button.
During registration, the user provides:
Username
Email
Password
Role (either Client or Freelancer)
Post registration, an email confirmation is sent via Amazon SES.
The email confirmation works correctly; when a user clicks on the link from the email, they are redirected to a page indicating "Email confirmed, please log in".

Issue:

Even though the user is correctly created and the email is confirmed, the login controller doesn't authenticate the user.
The direct password insertion into the database has been tried without hashing for simplification. Yet, the issue persists.
Attempts have also been made with hashed passwords, but still, the issue continues.

Task for the Freelancer:

Investigate the reason behind the login issue.
Resolve the problem ensuring that users can log in successfully after registration and email confirmation.
Ensure password security best practices are maintained (for instance, passwords should be hashed before being stored in the database).
Document any changes made and provide feedback on any other potential improvements identified during the troubleshooting process.

The bug will be considered resolved once the user demonstrates the fix, submits a Pull Request, and we confirm that the changes are functioning correctly on our end. Payment will be released upon successful verification.