Add accessibility to existing web app

I have simulations developed in JavaScript and it's libraries. Everything is running fine. Problem is it does not follow WCAG 2.1 level AA guidelines. I need a full time freelancer with strong knowledge of HTML5, CSS, JavaScript and accessibility implementations. Understanding of WCAG 2.1 is must.
Please provide your sample work of same kind with your bid. Budget is INR 4000-6000.