Xway will run on macOS 10.14 or later, 10.14 being the last version of macOS that Freeway can run on. I’m not sure if it’s possible to upgrade from 10.13 to 10.14 any more but if you can, that would let you run both Freeway and Xway on the same computer.
This will download a 30-day trial version, which can be converted into a licensed version by purchasing a licence (which you can do at a discount, if you have a serial number for Freeway 5.5 or later.) The latest version of Xway can read old documents, but 0.6b6 can’t read newer documents.