1. Save the file, then find it in your Downloads folder. It is about 120MB, so give it a minute.
2. Right-click it and choose "Extract All". This matters: if you open the zip and double-click the app inside it, Windows copies out only that one file and the app will not start. It needs everything in the folder.
3. Move the extracted folder into your user folder — the one holding Documents and Downloads, so the path ends up like C:\Users\yourname\HossTrain. Not Downloads itself, which people empty, and not the root of your C: drive: Windows protects that, and the app needs to be able to replace its own folder when it updates itself.
4. Open the folder and run HossTrain_app.exe.
5. Windows will warn you that it protected your PC. Click More info, then Run anyway. This is expected: the app is not code-signed yet, which is a certificate we buy rather than anything about the app. You should be suspicious of that warning on software you did not expect — this one you did.
6. To get an icon on your desktop: right-click HossTrain_app.exe, choose Show more options if you are on Windows 11, then Send to → Desktop (create shortcut).

There is no installer yet, so the app lives in that folder rather than being installed. To remove it, delete the folder.