Using Cloudinary with Heroku - heroku

Question

I'm trying to use Cloudinary to handle the upload of images in my app. I created a Cloudinary account for it and this works perfectly in production.
I've deployed my app to Heroku and can't managed to successfully connect my Heroku app with Cloudinary. My app appears online but the images stored in Cloudinary don't display + the upload function doesn't work as well - i guess it's because the link with cloudinary is broken so the server doesn't know where to get the images or store the files.
I've first manually added the Cloudinary Url in Heroku's config vars and it didn't work. I then installed the Cloudinary add-on on Heroku and, when I install it in Ressources, Heroku redirects me to a newly created cloudinary account (it seems that adding the Cloudinary add-on to heroku creates a brand new Cloudinary account).
My problem is that I want to use my existing Cloudinary account in my Heroku app and I can't figure out how to connect both.
in my code, i'm storing my details in an env file, and on the server-side, I'm using my account details like so:
require("dotenv").config();
cloudinary.config({
cloud_name: process.env.CLOUD_NAME,
api_key: process.env.API_KEY,
api_secret: process.env.API_SECRET
});