To test the application you have just created, your Facebook account must be confirmed as a Facebook developer account – see Creating a Facebook Developer account.
To check that you have a developer account, follow the instructions here – My Facebook account is not a Facebook Developer account. What should I do?
Your account must also be added as an administrator or tester for the application – not just the Facebook page.
For how to add a Facebook account as an administrator or tester see How can I add a Facebook account as an administrator or application tester.
If your are admin of the Facebook page where the app is installed, you shall be blocked during the user flow. To avoid that, you should be added as an admin or tester of the application.
If your account is already Facebook Developer-certified, you should check that your account is admin of the application you want to access. To check this, see how you can add someone as an application tester
If problems persist, an error may have occurred during the creation of the application. Contact us.