You must check the Enable Event Placeholder Step checkbox field in the Setup Information section of the Conga Orchestrate Setup. This setting creates the sub_type__c field.

When a process step is an Event Placeholder, Conga Orchestrate waits for an Event with a matching Sub-Type to be created before child step(s) can execute.

To configure Event Sub-Types:

  1. In Setup, use the Quick Find and start typing Activity Custom Fields.
  2. Select Activity Custom Fields. 
  3. Select the field label Sub Type.
  4. Select Edit next to a Sub Type Value.
  5. Enter the Sub Type Label and API Name and click Save.
  6. Repeat for all needed Sub Types.
  7. Click the Deactivate link next to any values not in use. t-event-sub-types