Download Instagram audio — without the video.

Screen recording a reel just to keep the song is the old way. There's a faster path that ends in a clean MP3.

Saved

Copy the reel link in Instagram. Share icon → Copy link. Same as any other reel.
Open ReelGrab and switch to the Audio chip. Paste the link in the box, then tap the Audio pill so we know to extract just the sound.
Hit save. You get an MP3. Up to 320 kbps, named after the reel. Drop it into your music app, your Voice Memos, or your video editor.