Hey there @ssaid11 o/
Hope I can be of assistance here, if assistance is still needed
Your question is a bit confusing, so perhaps some clarification would be helpful. You say:
will I still receive a repository creation event when a new repo has been created even though the app is not installed on the new repo?
The screenshot you linked, shows the webhooks being subscribed to by your app. So if your app is installed on a user account, or Organization, but only granted limited scope to a specific repository, or repositories, then no. You would not receive notifications that new repositories are created, which do not grant access to your application.
The user would have to grant your application permission for all repositories either within their Org, or user account, in order to trigger webhook events, that would notify you of newly created repositories.
I really hope that helps, even though it’s been quite some time since you posted.