Revamp of Cryptocurrency Learning System

I have inherited an older learning management system that teaches cryptocurrency and blockchain-related education. The platform already exists and has users, courses, lessons, quizzes, progress tracking, certificates, admin features and some access/payment logic... (Budget: £3000 - £5000 GBP, Jobs: API Development, Blockchain, Cryptocurrency, Database Design, JavaScript, MySQL, PHP, Project Management, Software Architecture, Web Development)