Hi KWILSON117,
So there’s a couple of ways which Flow could be useful depending on your exact use case. The criteria you mentioned (3 or more orders and less than $150) can be modelled in flow as shown in the screenshot below by looking at the order.customer.numberOfOrders and order.customer.amountSpent.amount fields that come from an Order created trigger. This will include the current order as well as all previous orders, so if they are returning their order the current order may put them over the $150 threshold.
If your goal is to create a notification when a customer who previous had a return creates a new order, something more like the following workflow may be better. The workflow will fetch all previous orders from the customer that are in some state of a return, count how many there were and then check if that number is greater than zero before sending a notification.
To do this, you’ll want to use the following query in the Get order data step’s Advanced query mode and ensure you set the Maximum number of orders to 100.
customer_id:{{order.customer.legacyResourceId}} AND return_status:"return_requested,in_progress,returned"
Hope that helps!