How can we compare the true labels to the predicted labels?

Hi,
It is really cool competition. Unfortunately, we could not join this competition. I wish we could. But, I have checked the most of repos and I have realised that "True labels", considering that file 'blind_stuart_crawford_core_facies.csv', have 890 data when the predicted submissions of teams have only 830 data. Is it a mistake or update in the repo? How can we decide our test accuracy ourselves? Thank you for your time,
Vural