Hi err’body!
I’m needing some help. I’m trying to create a post-purchase flow that is specific to collection (i.e. a customer has made a purchase on our site and has selected “collection” instead of delivery). My site is built on WooCommerce.
Crossing fingers that someone has the answer for me! 
Welcome to the community
You can do this. Create a flow with a trigger of placed order. Add a trigger filter with a dimension of ShippingMethods equals collection. The example below is for Free Shipping in a WooC set-up I have.
Only customers who place an order AND have a collection as their ShippingMethod will trigger/enter this flow.
Alternatively, you could have one post-purchase flow (placed order trigger) and use a trigger split for to select collection customers.
Hope that helps
Andy
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