How do I add automation to complete the parent request based on state of subtasks?

Step-by-step guide

Go into Modules.
Open the Module that you want to add the automation for.
Go into the Workflows tab.
Navigate into the Users Actions by selecting Next or selecting the Actions tab.
Add a new Action to be used with the automation. In this case it is named Auto Complete.
Select the Start States. These are the states the automation will work for.
Set the End State in this example Competed.
Set the Permissions. By giving just Tenant Admin role permissions the other roles will not see the new state that is only needed by the automation.
Select the Conditions tab.
Then, select SQL Where Clause option.
In the Expression field enter the logic for when the automation can be performed. Here is an example –

MainTaskId = %(BLEntityId)% and not (State = "Completed" or State = "Cancelled" or State = "Deleted" or State = "Recount Requested")

12. Select Okay.

13. Select Save when complete.

14. Next select the Automations tab.

15. Use the +Add Button to start a new automation.

16. Give the automation a Name and Description.

17. In the Workflow action to perform dropdown select the action that was created in the earlier steps (Auto Complete).

18. Select the Criteria Tab.

19. In the Select Source Field to base the automation on and continue to add the desired criteria. You will be able to see the criteria as you add it in the Expression section (see example below).

20. You can use the View Matches to see how many records meet the criteria you have set (it will not consider any criteria in the Action).

21. Select the Frequency tab to set the frequency you want the automation to run.

22. On the General Tab you will need to select Enabled and Update to finalize the setup.