Hello my name is René. I have been working as a programmer for 3 years, I have a lot of experience in different programming languages and frameworks, I can help you with what you need, if you want to see my CV, let me know and I will send it to your email
In order to send the invoice to the user's email, it is necessary to create a backend for example with NodeJS, react is not a backend, I can do the aforementioned, let me know.