I'm having the same problem as Beesmm below me! It says it needs to be updated and can't be scanned for viruses so they won't let me install it! Excited to try eventually though!
I'm still figure out the "need to update" part but the "cannot check for malicious software" is a standard message that comes up because I'm not a part of Apple's developer program. As long as you only get StimuWrite from official sources (this page currently is the only one), you'll be safe.
Try this:
- Drag the app into your applications folder.
- Open the Finder and navigate to the application.
- Right click or control click the StimuWrite icon and select open.
- Click the Open button that comes up and it should open and not give you a warning anymore.
You can find more info on the apple website here. I hope that helps!