The old link referenced pointed to a different page, the release page for the previous version.

Perhaps the biggest difference between Permanent and Numbers is the interface. It's easy to suggest that tablet spreadsheets might all work the same, but if you try a few you'll find they are widely different experiences.

Permanent has cloud support for Box and Dropbox. Numbers supports only iCloud.

Permanent is free, and most people do fine with the free version, so a pro upgrade is generally not required to use the app.