The Fire TV series of devices are more closed to 3rd party applications by default and require a few more additional steps to install the RES app. This process is known as sideloading and is necessary to install APK files from other sources. If you have not previously done this you can follow the guide from start to finish.
Enable Unknown Sources
If you have not already you will need to enable Unknown Sources. If you have already done this, you can skip to Installing Downloader app.
Click on Settings menu option on the home screen.
Click on My Fire TV. Some models may show Device instead.
Click on Developer Options
Highlight and Click on Apps from Unknown Sources
Click on Turn On to enable Apps from Unknown Sources.
Downloader is an app that allows you to install APK files from any location. If you have previously installed it you can skip to Installing RES app.
To start, click on the Search icon
You will see an on-screen keyboard. Enter “Downloader” in the search field.
Once you have entered the text, choose the first option on the list, it should be “Downloader”.
You will be taken to the search results screen. Highlight and choose the Downloader app.
The Downloader information screen will now display. Click on Get, or if you have previously installed it, Download.
It will take a few moments to download and install. If it fails, try downloading it again. Once completed, click on the Open icon.
A notification will display to give permission for Downloader to access files on your device. Click on Allow.
Installing RES App
If you have not already, open the Downloader app. Highlight the URL area and click on it.
Using the on-screen keyboard, enter http://bit.ly/2RVmW4d The URL is case sensitive so enter exactly as shown. Once entered, click on Go.
If you have entered the correct URL, the Downloader app will proceed to download the RES APK file. If you receive an error message, please check the URL and enter it again.
Once it has completed downloading, you will be prompted to Cancel or Install. Click on Install.
After a few moments, the installation will be completed. You can click on the Menu button to open the RES app immediately.
To locate the RES app in the future you can find it in your apps list. From the home screen, scroll down to Your Apps & Channels and press left once to See All and click on it.
You will find the RES apps on the list of apps, simply highlight it and click on it to open the app.