Thanks for reporting.
I’ve had several beta users have reported issues with PhotoStructure on Windows when using third-party antivirus/antimalware packages.
Due to these false-positives, and the fact that these software packages have a history of security issues themselves, PhotoStructure on Windows is only supported when used with Microsoft Defender Antivirus.
Microsoft Defender Antivirus is the free and built-in antivirus for Windows 10 that was previously called Windows Defender.
I recommend all my Windows users get in the habit of using https://www.virustotal.com to scan any download. VirusTotal isn’t software you install: it’s a website that you drag the downloaded app onto, and it scans the app with some 50-odd virus scanners for free.
Here are the VirusTotal scans of the .7z installer package for v0.9.1 (one for the file, one for the URI):
And for v1.0.0-alpha.7