Writing a python API which creates a list of the selected checkboxes (from an existing website) for input into a backend python script

I am trying to write a Flask API which takes the selected checkboxes from a webpage and puts them into a list to be inputted into some backend python scripts that I have written. The website is being created by a different company. I have watched/read multiple Flask introductions and even written a piece of code which creates a list of checkbox inputs (see below). However the below code is only being run on a development server and I need to be able to integrate this api into an existing website and for it to be called on the click of a button. I tried to look for resources on the web on how to do this but have had no luck. I am very new to Flask and fairly new to python so any help would be appreciated.

from flask import Flask, jsonify, render_template, request



app = Flask(__name__)


@app.route('/tickboxes', methods = ['GET', 'POST'])
def tick_boxes(): 
    if request.method == 'POST':
    
        chosen_categories = request.form.getlist('mycheckbox')
    
    print(chosen_categories)
    return chosen_categories
return render_template('checkboxes.html')


if __name__ == '__main__':
    app.run()

How can I convert this to use on an existing website?