Sorry that you’ve run into issues! As we shared some time back, Bootstrap Studio 6.5 is built upon a new Electron version which does not support Windows 7, Windows 8 and Windows 8.1. Ubuntu 16.04 is quite old and hasn’t been supported for a couple of years as well.
The app won’t auto update if you run an unsupported Windows version, but we don’t have such checks for old Ubuntu releases so it will auto update there.
In either case, you can switch off Bootstrap Studio updates and keep running an old version for as long as you need.