Only the first page of the score is imported from .pdf

Hi everyone, I'm new to MuseScore and just trying to import some .pdf scores to edit, translate etc by this URL: https://musescore.com/import.
Sometimes I get all the score's sheets imported, most of times I only get the first page, where am I wrong?
I'll upload one of the files getting only the first page import just as anexample.
Thanks for any help!