Using Windows 7 and FileMaker 8.0. Can Libre Base open and save these files?
Have no personal experience with FileMaker but it appears there may be two possibilities.
First would be a connection to the files through Base. See this post → FileMaker Pro 13 to Base
The other would be to export the data via a csv file and import this into Base connected to a database. See this post → filemaker tables to libre base