Integrating a private zendesk app with fly.io

Creating application approach:

I have created a private zendesk application with that HTML file and a server-side application integrating it with ChatGPT.  The idea is to enhance the emails shared by the engineers in a more formal and technical manner.  

We are using a .env file to store the OPEN_API token to access the OPEN API endpoint and the application is working perfectly during testing. 

Now, uploaded the project to github and deployed the server side application on fly.io. The front-end of the application is compressed and uploaded to zendesk. Though the front end is working, we are not getting any response from server side application.