Pages does not support the OpenDocument Format (ODT) documents created by OpenOffice and LibreOffice. Your best bet is to use a current version of Word that can open and convert ODT files to Word (.docx), or install the free LibreOffice Suite (7.3.3), open the ODT file in LibreOffice Writer, and then save it as a Word 2007 - 365 document (.docx). Then you can open that Word document in Pages and it should be translated into a Pages (.pages) document.
Pages is pretty fussy about Word content, so if there are font references in that ODT document that are not installed on macOS, or Word-specific content, then Pages will force font substitution and may drop unsupported document features. There are many other "Word" features that Pages does not support, so you will have to open the Word document and see what happens.