Are you having an issue with Screenwriter crashing the moment you select FILE > Save As or FILE > Open?
It may be that your DEFAULT DOCUMENT folder path is set to point to a cloud-based drive (iCloud, DropBox, etc). These always-syncing cloud-based folders can cause problems for Screenwriter, and we don't recommend you set your Default Document folder to be "in the cloud".
The DEFAULT DOCUMENT folder can be viewed and set from Screenwriter's Preferences dialog, on the FILES tab:
You may need to move your script documents folder back to a non-cloud location. In some cases, you may need to turn off iCloud Drive / iCloud document syncing to achieve that. However, Write Brothers cannot advise you on that process. Make absolutely certain you have proper backups of your scripts BEFORE you change any of your iCloud sync preferences.