Even though you have finished the process of inviting a user, the invited user did not receive the invitation to create its own account.
Below we have created for you a checklist with things that might have gone wrong and what actions you should take accordingly.:
Ask from the invited person to check the spam folder in case the email has been moved there.
Check your application user list to verify that the invitation has been sent. If the invited person is not included in the user lists, you should repeat the process one more time to make sure that the invitation has been saved. Remember to choose a role for the new user.
Try another email to make sure that the the specific recipient doesn't use an email blocker.