Ok, I had to do some lookup as to the IR diff and CI Diff (IR diff seems to refer to rate, while CI diff seems to refer to proportion of people (ie: per person, not per time). In either case, Atlas can’t help you here because you are going to want to do is calculate the incidence proportion and incidence rate between the PS-matched populations with Time-At-Risk of 6mo, 12mo, 18mo and 24mo. You could do this using the CohortIncidence package if you can extract the PS-matched subjects from each cohort, and do the analysis only on those two sub-cohorts. You’d then specify the 4 time at risk windows, and calculate the difference of rates/proportions.
If you are familiar with the output from Population Level Estimation pacakge, you might be able to get the answer you want by definign the 4 time at risk windows, and caculating each IR/IP by counting the distinct people with cases / distinct people or cases / total follow up time. You’ll need to ask someone more familiar with PLE package for specific instructions on how to configure the analysis to do that, but I believe you just need to specify the additional time at risks so you get the result for each time window.