Hi there.
So if you will configure it a Ring group and assign DID, the call will flow to that Ring group and you will see in your inbound rules too (in the Dashboard > Inbound rules report). Now the option where for the Default route, is in case you did not create a rule, or maybe you removed your Ring group, so the call will to the Default route.
Make it simple, check Inbound rules report, and if your DID is not pointing to the specific destination it will go to the Default route.