How to Install Subtitles On Kodi on FireStick / ChromeCast [OpenSubtitles and A4KSubtitles]

A4KSubtitles:

https://a4k-openproject.github.io/a4kSubtitles/packages

OpenSubtitles:
*Before beginning - an account on ‘OpenSubtitles.com’ is required.

The repo for OpenSubtitles can be installed within Kodi’s add-on repository.

Go over to the ‘Add-Ons’, ‘Install from Repository’.  From there go down to ‘Kodi Add-on Repository’ and find ‘Subtitles’

Once there; Find ‘OpenSubtitles.com’. Click it and install it.
On that same screen; go to ‘Configure’ and enter your details after registering to ‘OpenSubtitles.com’ and click ‘Ok’