Currently, the instructions say that
“
Setup Incoming Support
To receive events from your Jira Cloud site you need to enter the url for your site in the Url field.
Setup Outgoing Support
To allow outgoing requests to your Jira Cloud site you need to authenticate as the user that those requests will act on behalf of.
“
and I’m pretty sure that authentication is required for both incoming and outgoing flows.
we will be overhauling the UX of the connection screens in the coming weeks. Hopefully some improvements coming soon.