How To Install Downloader on Firestick/Fire TV

 From the home screen of your device, hover over the Find option.

 

Click Search.

 

Search for and select Downloader.

Choose to Downloader App.

Click Download.

Wait for the app to install.

Once the app finishes installing click Open.

Return to the home screen and open Settings.

Click My Fire TV.

Choose Developer options.

Click Install unknown apps.

Find the Downloader app and click it.

This will turn Unknown Sources to On for the Downloader app. This will enable side-loading on your device.