Install it on a Windows PC or in a Virtual Machine - or on a Mac that runs a compatible OS - so that you can access the files.

There are a few Macs introduced in 2024 that can only run Sonoma and the upcoming Sequoie. If you have a 2023 or earlier Mac, you have an easy workaround. APFS Volumes are like partitions except that they share empty drive space. This has been around since High Sierra for SSDs and works on mechanical HDDs since Mojave. My new 2023 M2 Studio can run Ventura, Sonoma and Sequoia or all three, for example.

To create a dual-boot Mac nowadays, say Sonoma and Ventura or Monterey (either can host 26), create an APFS Volume in Disk Utility and install that OS onto it. It's really easy and you can download the macOS installer from the App Store. Apple has a ton of Support docs on this and phone support can walk you through it as needed.

https://support.apple.com/guide/disk-utility/add-delete-or-erase-apfs-volumes-dskua9e6a110/mac 

Once you have this bootable Volume up and the OS installed, you can download 26 from your MM Account and install. It will work like before. Other threads have instructions for batch-converting multiple Finale Files to PDF and MusicXML (3.1 if converting from 26).

If you take the crossgrade to Dorico Pro 5 offer, you will get a license for Finale 27 at no charge. This gives you MusicXML 4.0 that has more functionality than 3.1. Dorico Pro, Sibelius and MuseScore 4 all support xml 4 imports.