Jacob,
Thanks for posting to the forums.
The invalid file type is an issue I and TWS are currently attempting to resolve. In the mean time, since the other template files open without issue I would use one of them to work from. The Ensemble template may be the easiest to use. Open the file and then delete those staves and instruments you don't need. All of this may be done via the Score Manager and the Audio/MIDI menu.
Let me know if you have any further questions of issues.
Thanks for posting to the forums.
The invalid file type is an issue I and TWS are currently attempting to resolve. In the mean time, since the other template files open without issue I would use one of them to work from. The Ensemble template may be the easiest to use. Open the file and then delete those staves and instruments you don't need. All of this may be done via the Score Manager and the Audio/MIDI menu.
Let me know if you have any further questions of issues.