If you have your own video files and need to add external subtitle files (usually in .srt format), these communities are the primary sources:

Addic7ed: Highly recommended for TV series, often featuring faster updates for various languages.

Frequently available on streaming sites and through physical media like the Season 1 DVD.

OpenSubtitles : A major database where you can find community-uploaded subtitles for all seasons, including specific translations like Spanish.

Standard [CC] is available on almost all digital platforms.