Given I have a PC with LibreOffice 6.3 newly installed, how do I "download and open" (or whatever the terminology is) an e-mailed "Pages" document?opening pages

When I click on the e-mailed attachment (i.e., the document sent in “Pages” by a Mac-using client) in order to “download and open” it (so I can save it in my files), I get a pop-up window that says: “The file cannot be opened because there are problems with the contents.” Then, when I click “OK,” another pop-up emerges that reads: “Word found unreadable content in [name of file]. Do you want to recover the contents of the document?” When I click “Yes,” the original pop-up arises again (“The file [name of file] cannot be opened because there are problems with the content.”

I’m certain there are no photos, graphs, charts or illustrations in this document (it’s simply text written on a Mac in “Pages” format)… but I’m too much of a novice to know what to do/how to use LibreOffice to get this document open.

Can anyone help me?

And what got this problem to do with LibreOffice? You have received an email (the app used you didn’t tell but it’s definitely not LibreOffice), the email has an attachment which seems not to be in ODF format (but .pages format) and thus again not related to LibreOffice. And you tried - obviously - to double click onto the attachment, and now Word (assuming you also have MS Office also installed and associated to the file type of the attachment) is throwing an error message - And Word is not part of LibreOffice. So I don’t see a reason why you asking here.

Use a Save As method of your email application, and save the attachment to your - let’s say - document folder. Use Finder, go to your folder where you’ve saved the attachment to and use Right click -> Open With -> Other and select LibreOffice.app to get the file opened with LibreOffice (will only work if the attachment’s file type is supported by LibreOffice, which is true for .pages files)