Files with these names almost always require a password provided by the original uploader or the forum where the link was found.
Compressed RAR archive (Part 1 of a multi-part set). c1d1455ef5534dba85de2182def8a09a.part1.rar
Verify the site where you obtained the link. If it’s from an untrusted pop-up or a "free download" search engine, do not open it. Files with these names almost always require a