Yes, that is the correct label file for the Particulate Matter track (but not the Trace Gas Track). The first few lines of the corresponding metadata file should look like:
granule_id
20180201T191000_maiac_la_0.hdf
20180202T195000_maiac_la_0.hdf
20180203T203000_maiac_la_0.hdf
20180204T194000_maiac_la_0.hdf
20180205T202000_maiac_la_0.hdf
Note that the granule ID timestamps won’t match up exactly with the train label data. Here’s another thread on that topic: Clarification on features' dates used for prediction - #2 by Carl_Malings