Scheduler executes cases in the same order as they are shown in case explorer from top to down including sub folders.
However, you can change cases order in explorer by dragging and dropping and then editing and saving your schedule. Refer below:
If user wants to run 'Automation case 1, 2' from project UAT and 'Automation case 5 and 6' from project Production then, as a first step user has to set the order of flows in Flows section (shown in first screenshot), after that user need to select the Flows to run in schedule (shown below).
At the time of schedule execution order present in Flows section will be followed.
For any clarification, please contact our Priority Support.