You may encounter a warning from Microsoft Defender's SmartScreen when trying to install the JamKazam app.

See the image below:

1. Click the "More Info" link below the waring message.

You will now see two buttons at the bottom of the Window.

See the image below:

2. Click the "Run anyway" button to proceed with the installation.

You can proceed to sign into the app after your app launches and you reach the home screen.