Click on the A/B test you want to track Heatmap data on and then click Edit A/B test.
1. In the editor now click Settings
2. Click Heatmaps
3. Click Create Heatmap for project variations.
4. If you want to set up another for this test click New Heatmap otherwise close this popup by clicking the x. 
5. Go back to the dashboard and click on Heatmaps
6. Find your heatmap and click it.
7. Click Configure heatmap
8. Click Edit Audience
9. Set the same Audience as in the A/B test.
10. Click Save Audience and then close Audience settings by clicking the x.
11. Click Save and close and you are done!