The country I live in doesn't support Shopify Payment. Therefore, I use 2Checkout payment as third party payment provider.
I'm now setting up through the instructions Shopify gave. But am curious about the Instant Notification System (INS) section in 2Checkout account. Do I need to enable it? The instruction didn't mention it.
Hope you are doing well!
I just came across your post and I believe this field is optional and it's just for opting to receive information about your orders via HTTP POST to a URL you specify.
You can check out more about this in below link.
Hope it helps!