From this detailed guide, you can learn how to install NextGen RT TV Series Addon On Your Kodi.
NextGen RT TV Series Kodi Plugin. Browse and stream RT Documentary TV series directly in Kodi. This plugin is not affiliated with or endorsed by RT (Russia Today).
this installation guide applies to all compatible devices including Amazon Firestick, Fire TV, Android & iOS, Mac, Windows, Android TV, Android Boxes, etc.
How To Install NextGen RT TV Series Kodi Addon
- Open Kodi
- Be sure to have the Unknown Source box checked as Kodi requires this before installing 3rd party add-ons.
- HOME Screen > Add-ons > Settings button 
> Add-ons > Enable Unknown Sources.
- From your Home Click Settings (cog icon top left)
- Click File Manager
- Click None
-Type in the following EXACTLY https://tinyurl.com/nextgenrt
- Click OK
- Click back on your remote/keyboard
- Click Add-ons
- Click Install from Zip File
- Click nextgenrt
- Click repository.nextgenrt-1.x.x.zip.
- Wait for Add-On Enabled Notification
- Click Install from Repository
- Click NextGen RT Repository
- Click Video Add-Ons
- Click NextGen RT TV Series
- Click Install
- Wait till you can see the message Add-on installed pops up. That's it! You can now find you addon from main menu > Add-ons, enjoy.