There are three common issues when trying to install the BitBoxApp on Windows:
Missing admin permissionsIn order to install an application on Windows you need to do so with admin permissions. Usually this is done automatically but sometimes you need to enable it manually. To do that, right-click on the downloaded BitBoxApp.exe file and select "Run as Admin".
Older BitBoxApp version already running
Only one BitBoxApp application can run at the same time. If you are trying to install a new BitBoxApp version while an older version is still running (could be running in the background), first completely quit the old BitBoxApp and then try the installation of the new BitBoxApp version again.
Microsoft defender blocking installation
On some Windows versions, Microsoft defender blocks the BitBoxApp installation.
If you get a popup that says something like "Windows protected your PC", click on "More info" and then select "Run anyway" to proceed with the installation.