If your panel shows that a campaign is "pending statistics," it means it's time for you to submit the statistics for your post.
For Instagram, accessing statistics is quite straightforward:
1. First, go to your profile and in the upper right corner, you'll find the menu (its icon is three horizontal bars).
2. Tap on it, and then click on "Insights" or "Statistics."
3. On the first screen, you can see your posts. If you click on "View All" afterward, you can filter by time and view the statistics post by post.
Here's a link to a comprehensive guide to help you understand Instagram statistics thoroughly.