Clarification on features' dates used for prediction

I don’t have an answer, unfortunately, but rather a related question. In the problem description it states:

“You may use historical ground truth training data as feature input to your model. Note that for verification, you may only use historical data up until the point of inference in order to make your prediction.”

Does that mean that we would have access to the ground-truth data from up to the day before we are trying to predict the concentrations for, which can be used as input data into the forecast algorithm? As a more concrete example, if I am trying to predict the concentration at a location on January 2, 2021, would I be able to know the concentration on January 1, 2021 and use that to inform my forecast? Or does this only apply to data from the training period provided for the competition, but not for the testing or for any validation periods?