Server Error in '/' Application when activating "Nintex Forms" web app feature.

Apparently "INSTALL-NFService" need to be run in SharePoint PowerShell to fix this problem.

 

When I installed Nintex Forms again,

I can't add license, because I got message that "Nintex Forms has not been activated yet.

Please go to Central Administration and activate the Nintex Forms under Web Application > Manage web application > Manage Features