UI UX Designer for a website and app

I am looking for a UI UX Designer who can design a website and app with the primary goal of selling a product/service. The project requires both desktop and mobile designs that must be responsive. I have an existing design to follow, so the ideal candidate should have experience working with existing design guidelines. The designer should be able to create a visually appealing and user-friendly interface that enhances the user experience and encourages conversions. Experience in e-commerce and mobile design is a plus.