How to stop simulation run after specific time NOT tick

Here's a quote from a recent paper re. the tick concept that might help.

Events in Repast simulations are driven by a discrete-event scheduler. These events themselves are scheduled to occur at a particular tick. Ticks do not necessarily represent clock-time but rather the priority of its associated event. Ticks determine the order in which events occur with respect to each other. For example, if event A is scheduled at tick 3 and event B at tick 6, event A will occur before event B. Assuming nothing is scheduled at the intervening ticks, A will be immediately followed by B. There is no inherent notion of B occurring after a duration of 3 ticks. Of course, ticks can and are often given some temporal significance through the model implementation. A traffic simulation, for example, may move the traffic forward the equivalent of 30 seconds for each tick.

If you want to schedule a stop after some amount of walltime (e.g., 5 minutes) has elapsed, you could schedule an action that gets the time at its first invocation and then subsequently checks if the correct amount of time has elapsed. At that point, you could call RunEnvironment.getInstance().endRun(). How to do the time arithmetic is a Java question, so if you google for "Java time elapsed" or something like that you should get an answer.

As far as scheduling the action, you need to create a class that implements IAction (https://repast.github.io/docs/api/repast_simphony/repast/simphony/engine/schedule/IAction.html) and schedule that at whatever interval seems appropriate.