How to connect the work of the file application and the nginx server to process its requests?

Question

Nginx

Trying to track requests/responses between a 3rd party file application (closed) accessing an nginx based serverand the server itself. The server has just been installed (fresh) and I'm trying to understand which folders the application accesses, what files it tries to scratch and download in them. I tried the metric, it turned out not quite what you need. Apparently you need a person who is at least a little versed in the reverse. In the application, using a hexadecimal editor, the address of the host accessed by the application can change (elementary), but then there was a plug. The folder structure on the file server is more or less known. You only need to put the files of the desired name on your hosting in the appropriate folders, and you can undo the address of the call either by tracking requests / responses, or by using reverse, I believe. The point is simple. Make your own server for certain files using the application.
What do you advise, dear experts? Can someone suggest something useful?
Thank you.

Answer 1

Look in the logs, you can see what files the application requests.

Answer 2

Look in the nginx access log. For each request there will be a URI. Then you can either create a folder structure that matches these requests, or create a set of rules in the nginx config.