If you add/create the new listing in Hostfully first, and turn it ON under the Vrbo/HomeAway channel it will automatically be created on Vrbo/HomeAway. If it was created in Vrbo/HomeAway first the property can not be imported into Hostfully; it will have to be created in Hostfully (or imported from Airbnb if it exists there).
If your agency is a Pay Per Booking customer, the listing will automatically go live when all the minimal content conditions are satisfied. The platform will throw an error message indicating there is missing information if you haven't met that minimal content.
If your agency is a Pay Per Subscription customer, you will have to go into the Vrbo/HomeAway dashboard and make sure there is an active subscription attached to the property for it to go live.