Loacation of openvidu source code on server

we installed our openvidu on a local server via docker( Deploying OpenVidu on premises).
it is working well and have video calls but i want to change the UI of it but dont know where is the loaction of installed files and folders on our server.
this is all the files i see on server:

but no file or source code relevant to it !!!
where is the source code on server?

The application is inside a Docker container.

If you want to chage the UI, you should follow this documentation: OpenVidu Docs