How to automate the work with the site? Pull api? Somehow else?

Question

API

Advise what tags to put, otherwise I don’t know.

There is a cloud service trainbit.com, which provides 5 TB for free. But it has neither desktop nor android clients, it can only be downloaded through the site as separate files, which makes it difficult to work. There was an unobtrusive idea to automate work with the cloud in order to set up autoload, autosync and something else (the freedom of action is great). But how to do that?

I got into the interception of requests, only learned how to log in, and saw that some kind of api was being used, the methods of which do not seem to work outside the cookie context.
It didn’t seem to work out that way, but if someone offers a way, for example, to understand the site code and understand how to do it, it will be great (I myself don’t know how to figure it out, and I don’t even know how much I need to study for this).

It is clear that it is possible to implement the work using selenium, but 1) it is inconvenient that some left browser will hang somewhere (although it seems to be possible to hide it); 2) this is extra work - first, an html document is formed from the received answers in a graphical representation, then something is pulled out of this document again, it would be more logical to work directly with requests; 3) it does not seem reasonable to try to shove selenium into android.

Thanks for helping those who help