Age output is built-in to the State Class output – it appears as another column in the base State Class output (both in the UI and through rsyncrosim). If you have age output working properly you’ll see an “Age” entry under the “Dissaggregate By” option for State Classes in the Chart window. Otherwise Age information does not appear for your model.
My guess is that you have perhaps not yet setup your ages in the project’s definitions for you library? See https://docs.stsim.net/reference/prop_ages.html for how to set these up. If you leave the Age Types blank then Ages are not tracked for your model. You may also optionally want to setup Age Groups to bin your ages in order to reduce the volume of your output.