This is the 16183rd most frequent Polish word.
umieszczonych
"Placed" or "located."
The participle 'umieszczone' is used to describe the location of the documents, specifically highlighting that they were actively placed in the safe.
Znajdowały się tam ważne dokumenty umieszczone w sejfie.
There were important documents placed in the safe.
Here, 'umieszczonych' modifies 'informacjach', indicating that the information in question was actively posted on the website, a completed action as part of their description.
Polegałem na informacjach umieszczonych na oficjalnej stronie.
I relied on the information posted on the official website.
In this sentence, 'umieszczone' describes the photos specifically as being actively organized or placed in an album, contributing to their descriptive state.