From this detailed guide, you can learn how to install Opensubtitles Addon On Your Kodi.
Search and download subtitles for movies and TV-Series from OpenSubtitles.org without log-in. Search in 75 languages, 6.000.000+ subtitles, daily updates
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 Opensubtitles 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://deklica.github.io
- Click OK
- Click back on your remote/keyboard
- Click Add-ons
- Click Install from Zip File
- Click Deklica
- Click repository.dexe-x.x.x.zip.
- Wait for Add-On Enabled Notification
- Click Install from Repository
- Click dEXE's Addons Repository
- Click Subtitles
- Click Opensubtitles
- 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.