Sending a CSV to R Shiny

I'm not too experienced(student and intern) with Javascript(and no experience with R), but my boss wanted me to deliver a website that can take in a csv file, then have a RShiny script(someone else made) and paste the output onto the website for him to see. I'm using nodejs for the website

I'm having some serious issue with trying to figure out how to get the CSV to the R script. I have tried searching up online and at a lost on what I should do.

I tried using ChatGPT and its making me do app.post and I'm confused on how the R script is even being called

I tried looking it up online and it says I have to use R server to show the r Web page and I have no clue what it means.

The last issue is how I should even have the Rshiny script attempt to receive the csv from the java attempts to post it.

Is there some other way I could approach this because I have been stuck at this for 3 days.