recieving push HTTP request in webGL project

A hosting site opens an Iframe for each user session in which a unity 2020.2 webgl project runs, the game generates a score that needs to be sent back to the hosting site along with the user ID (which the project doesn't have right now).

Is there an option for the server who hosts the iframe to push an HTTP call with the user ID to be saved in the game?

the game doesn't know its host or the session it's in, in order to send a call outside, it must have some kind of listener.