Dec 20, 2017, 15:1012/20/17
Hello!
The "15.3K" is not the total number of points you have collected, but the number of points collected for this particular step.
As you see, you have completed 3 steps out of 4. Three first steps needed 5K points in total.
The 4th step alone needs 20K points. Out of those 20K required points, you have collected 15.3K. Now you need to collect 4.7K points more.
I hope this explanation helped!