Why am I getting this error after installation?
[HTTP 500] [HTTP 409] App "TA-DUOSecurity2FA" already exists; use the "-update true" argument to install anyway
but it is not showing in the App bar.
Since the App doesn't have any pre-build dashboards or views yet, it's set to not be visible. It's current primary function is to add a modular input, so if you click on the data inputs in the settings menu you should see a "DUO Security 2fa logs" local input type. The configuration steps are listed in the Details tab or the App page on Splunkbase.