What is the relationship between the routing policy configured for the routing zone vs the routing policy defined in the connectivity template?

The routing policy primitive applies a routing policy to an application endpoint. This overrides the routing policy configured for the routing zone. You must select the routing policy that was defined in the blueprint (Staged > Policies > Routing Policies).

see https://www.juniper.net/documentation/us/en/software/apstra5.1/apstra-user-guide/topics/concept/primitive-routing-policy.html for detail.