Website Organization and Payment Streamlining

I'm the founder of a language school that is dedicated to teaching the Greek language. I offer individual classes and group courses and in the future I'd like to also offer asynchronous, self-paced lessons... (Budget: €1500 - €3000 EUR, Jobs: eCommerce, Generative Engine Optimization (GEO), HTML, Payment Processing, SEO, Shopify, Squarespace, Web Development, Website Design, Website Management)