There is an appendix on how to open Freeway documents in the Xway User Guide: “Appendix 3: Importing a Freeway website.”
This contains detailed information. You might want to skip some of these details initially, but it’s helpful to read (at least) the Summary section and the previous introductory paragraphs.
You will need to locate resources after you have opened a Freeway document. This is because Xway (like most modern Mac applications) is sandboxed, while Freeway isn’t. As a sandboxed application, Xway is unable to access resources until you give it permission via a file dialog. This process should be fairly painless if you follow the instructions in the user guide: Xway knows where inaccessible resources are located, and you can give it permission to access them by selecting them (individually) in the Resources view and clicking on the Locate button. This will open a file dialog that displays the folder which contains the resource. Click on Locate (or press Return) in the file dialog, and this will give Xway permission to access that resource along with any other resources that are in the same folder (or in a subfolder). Don’t select a specific resource in the file dialog: if you do that, you are giving permission for Xway to access that specific resource, but you are not giving permission for it to access other resources that are in the same folder.
To view the Xway User Guide, choose Xway User Guide from Xway’s Help menu.