After you have published a listing to Vrbo, you may see that the connection's status is "Pending", and that a "Show Errors" button appears by the relevant listing. This occurs when Guesty has encountered a validation error while trying to publish it. If you see the following error message when clicking the button, it indicates that a base price has not been set on the listing in Guesty.
"Error: Element 'nightlyOverrides': This element is not expected."
Add a base price to the listing. Once done, the listing's status will change to "Connected" within 24 hours.