Hi, and sorry for the trouble!
Thanks for reporting it. The problem came from a Microsoft component (the Visual C++ runtime) that is missing on some PCs and was needed to start the app. Version 1.0.1, now available on the download page, includes everything it needs, so nothing else has to be installed.
Since you have the portable version, just delete the old folder, then download and unzip the new one (or use the itch app, which updates it automatically).
Once the app starts, click "🔑 Free version" in the toolbar, paste the license key shown on your itch.io download page (and in your purchase email), then click "Activate" to unlock everything.
If it still doesn't work, I'll give you a full refund, no questions asked. In that case, the app should now show an error message. If you can, please send me what it says, or the file %APPDATA%\generateur_stickmen\erreur.txt, so I can fix it for everyone.
Thanks for your patience!