The a4kSubtitles add-on is designed for automated scraping based on IDs. If it fails, keep a backup subtitle add-on that allows (typing the name of the movie yourself).
In some cases, Kodi may incorrectly return a TMDB ID instead of an IMDB ID, causing a4kSubtitles to fail because it doesn't recognize the format. a4ksubtitles imdb id not provided