When first activating your account through the web portal, you may experience issues logging into the app. This will be because the app takes 30 minutes to sync with the web portal.
Once you have allowed 30 minutes after activation, you should be able to log into the app.
Ensure that all account details and password is correct when logging into the app.
If you are still unable to log into the app after allowing 30 minutes and entering all correct account details, then get in contact with the team who will help you with the issue.