Hello! Welcome to our community.
First, please make sure to check if you invited the user to the correct app. Then, the user should check if the app is appearing on Applications or SSO Integrations depending on the type of application.
Notice that the Auth0 application is only the reference that the application exists but the user won’t be able to work on it from the Auth0 Dashboard.
Please, let us know if you have any other question!
Thanks.