App Source Code Modification

I need a developer to make some minor modifications to an existing source code and generate an app.

Key Requirements:
- Design Changes: Update UI colors and themes, adjust layout, and incorporate new logo and branding.
- Feature Additions: Implement user authentication and push notifications.

Ideal Skills and Experience:
- Proficiency in the relevant programming language and frameworks.
- Strong UI/UX design skills.
- Experience with user authentication and push notification integration.
- Attention to detail and ability to work within the budget.