Translation:I have meetings every day, I'm very tired!
I'm not a native Chinese speaker, but I think 我 is implied to be the subject of the second phase, since it's the subject of the first. "Very tiring" isn't a complete sentence in any case, but it's short for "It's very tiring," which uses the schedule as the subject. So, probably not a great translation, but not really any worse than Duolingo's suggestion...
On every other lesson, the "I am" is assumed and is given in the English translation. In this one, we end up with the totally unnatural sounding "I have meetings every day. Very tired!". What's wrong with "I have meetings every day. I'm very tired." We should be marked on our comprehension of the Chinese text, not a random guess at the only acceptable English sentence. Reported 18th November 2018.