Be careful with third-party sites claiming to offer "audio track downloads." These files are often used to spread malware or are low-quality rips that won't sync properly with your video. Stick to the official Netflix app for the best (and safest) experience.
If you've downloaded the show but want to add an English audio track or subtitles, you can use video editing software or apps designed for adding subtitles and audio tracks. However, finding an English audio track specifically for Dark Season 2 that you can add to a downloaded version might be challenging without ripping the audio from an official source. dark season 2 english audio track download