Assuming that you have configured the application, on the plugin’s main page or in the “Configure OAuth” tab, you will find a list of applications.
Here, you can find the application name like shown:
What is redirect_uri?
When using OAuth/OpenID protocol, the client must make an authorization request to the provider.
This request has multiple parameters, one of them, is redirect_uri.
When the authorization request is made, the user is asked to sign in and authorize the application. After successful authorization, the user is redirected to the redirect_uri with an authorization code in case of Authorization Code grant type and with an access_token in case of Implicit Grant or with id_token, if OpenID flow is used.