I normally would suggest to take a few pictures from the website and put them into a Google, Tineye, or Yandex search and see what comes up on them. However, everything is locked up tight. No samples. The site is in Polish and that makes any tour over there very difficult. Myself, I have joined sites in the past that aren't English speaking. And yes, I did have issues, but those were the risks that I had to take.
Put these into a Google, Tineye or Yandex search. See if you can obtain a sample gallery of 12 to 15 pictures :
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They may be too small to do in a reverse image search. If they are, then you can just forget about it.
Now, if you want the pictures that baldly enough, then you may have to join the site. Unfortunately, that's what you'll need to do.