Cannot select existing VNET

[juhi24]

I'm trying to redeploy Opnsense using this template. I have deleted the previous related resources except the VNET called OPN-VNET. I'm trying to delpoy to this existing VNET by selecting it:

But on the review page it says it's going to create a new VNET called OPN-VNET-1:

I have found no way to deploy to an existing VNET.