html5: how to implement html package in centos with nginx (Unreal Engine 4.23)

I am trying to submit a fictional game on a website. I have done every step in this document and packaged the game. The packaged game runs on localhost in Microsoft Edge without any problem. Then I have copied the files to my server. The operating system is CentOS7 and I am using the nginx web server. The backend is written with Flask. But I can't see the game online. Here is the link from my website. As you can see, the game doesn't download, only some buttons are visible. There is no error message unfortunately.

do you have any idea