Проблема "GET / HTTP/1.1" 404 -

Зарание извиняюсь за глупый вопрос. Пишу курсовую и тиммейт делает бэкенд на пайтоне . Сказал что код не может найти главную страницу , а после вопроса что мне с этим делать ,просто скинул ссылку на стак. Сам на пайтоне ниразу не писал.
Что нужно: я хочу получить доступ к базе данных , но код не может найти сервер . Код на пайтоне :

import sys
import pymongo
from pymongo import MongoClient
from flask import Flask
from flask import render_template
from flask_restful import Api, Resource, reqparse, abort, fields, marshal_with
from flask_sqlalchemy import SQLAlchemy
import secrets
from flask_cors import CORS


app = Flask(__name__)
CORS(app)
cors = CORS(app, resources={r"/api*": {"origins": "*"}})

cors.init_app(app)
api = Api(app)

mycliend = MongoClient()
carddb = mycliend['carddb']
cards = carddb['cards']
users = carddb['users']

acc_args = reqparse.RequestParser()
acc_args.add_argument("username",type=str,help="username is required",required = True)
acc_args.add_argument("password",type=str,help="password is required",required = True)

card_args = reqparse.RequestParser()
card_args.add_argument("number",type=int,help="card number is required",required = True)
card_args.add_argument("pin",type=int,help="pin is required",required = True)

sendcard_args = reqparse.RequestParser()
sendcard_args.add_argument("number",type=int,help="card number is required",required = True)
sendcard_args.add_argument("pin",type=int,help="pin is required",required = True)
sendcard_args.add_argument("sendto",type=int, help = "receiver card number is required",required = True)
sendcard_args.add_argument("amount",type=int,help = "ammunt is required",required = True)


tok_field = {
    "token":fields.String
}
balance_field = {
    "balance":fields.Integer
}

class Login(Resource):
    @marshal_with(tok_field)
    def post(self):
        args = acc_args.parse_args()

        if len(args['username'])<1:
            abort(401,error="username can't be blank")

        if len(args['password'])<1:
            abort(401,error="password can't be blank")

        try:
            result = users.find({"username":args['username']})[0]
        except:
            abort(401,error="Card information is incorrect")



        if result["password"]!=args["password"]:
            abort(401,error="Password is incorrect")

        token = secrets.token_hex(20)
        result['token'] = token

        return {"token":token}, 200


    def options (self):
        return {'Allow' : 'POST' }, 200, \
        { 'Access-Control-Allow-Origin': '*', \
          'Access-Control-Allow-Methods' : 'POST' ,
          "Access-Control-Allow-Headers":"content-type"}


class getBalance(Resource):
    @marshal_with(balance_field)
    def post(self):
        args = card_args.parse_args()

        if len(str(args['number']))!=16:
            abort(401,error="Card format is incorrect")

        if len(str(args['pin']))!=4:
            abort(401,error="Pin format is incorrect")
        
        try:
            result = cards.find({"number":args['number']})[0]
        except:
            abort(401,error="Card information is incorrect")


        if result["pin"]!=args["pin"]:
            abort(401,error="Pin is incorrect")

        return {"balance":result['balance']}, 200


    def options (self):
        return {'Allow' : 'POST' }, 200, \
        { 'Access-Control-Allow-Origin': '*', \
          'Access-Control-Allow-Methods' : 'POST' ,
          "Access-Control-Allow-Headers":"content-type"}


class sendMoney(Resource):
    @marshal_with(balance_field)
    def post(self):
        args = sendcard_args.parse_args()


        if len(str(args['number']))!=16:
            abort(401,error="Card format is incorrect")

        if len(str(args['sendto']))!=16:
            abort(401,error="Card format is incorrect")

        if len(str(args['pin']))!=4:
            abort(401,error="Pin format is incorrect")

        if args['amount']<0:
            abort(401,error="Amount can't be negative")

        if args['number']==args['sendto']:
            abort(401,error="You can not send money to yourself")
        try:
            result = cards.find({"number":args['number']})[0]
        except:
            abort(401,error="Card information is incorrect")

        if result["pin"]!=args["pin"]:
            abort(401,error="Pin is incorrect")

        try:
            toresult = cards.find({"number":args['sendto']})[0]
        except:
            abort(401,error="Receive card information is incorrect")

        if args['amount']>result['balance']:
            abort(401,error="Insufishent funds")

        result['balance']-=args['amount']
        toresult['balance']+=args['amount']
        cards.update_one({"_id":result["_id"]},{"$set":{"balance":result['balance']}})
        cards.update_one({"_id":toresult["_id"]},{"$set":{"balance":toresult['balance']}})

        return {"balance":result['balance']}, 200


    def options (self):
        return {'Allow' : 'POST' }, 200, \
        { 'Access-Control-Allow-Origin': '*', \
          'Access-Control-Allow-Methods' : 'POST' ,
          "Access-Control-Allow-Headers":"content-type"}





def main():
    api.add_resource(Login,"/api/login")
    api.add_resource(getBalance,"/api/balance")
    api.add_resource(sendMoney,"/api/send")

    #carddict = {"number":4790729914729354,'pin':6769,'balance':0}
    #cards.insert_one(carddict)
    #result = cards.find({'number':4790729914729354})
    #users.insert({"username":"user","password":"pass"})
    app.run(debug=True)

    #print(result[0]['pin'])

if __name__=="__main__":
    main()

JS код

let url = 'http://127.0.0.1:5000/';

const xhr = new XMLHttpRequest();

xhr.open('GET', url);
xhr.send();