It depends on the amount of apple pie filling you want to cook and the pressure amount being used. For example, it will take about 8 minutes for the filling to cook if you use about 10 psi. There are many different recipes that you can use for making apple pie filling in an instant pot. Each of them will require the filling to be put in for a different length of time, but an overall estimate is that it will take about 10 minutes for the filling to cook evenly.
https://instantpot.wpengine.com/faq/