Are you on macOS or Windows?
If on macOS,
– are you using the ARM or Intel version?
– are you copying the app from the DMG into the Applications folder and running it from there? (There can be licensing issues if running the app directly from within the DMG file.)
If on Windows, what Windows version do you have?
If you reinstall 2.6.11, does the app, including the licensing, work as normal?
Could you email us the files from the old system you’re trying to load?