Once your ad is running, the Results tab on the ad shows you how it's performing. This is separate from your Link's analytics tab (which tracks overall Link traffic from all sources); the Results tab is specifically about what the ad itself has produced.
The main metrics
Breakdowns
Underneath the main metrics, you'll see how the ad is performing across different audiences:
Great for spotting a specific slice that's outperforming the rest. If your 18-24 US audience is converting at twice the rate of everyone else, that's useful information for the next campaign or other music promotion strategies.
Heads-up on data freshness
Numbers in the Results tab come from Meta and usually lag behind real-time by an hour or two, sometimes longer when Meta's systems are backed up. If a number looks stuck, give it a bit before worrying.