Thanks to the post that discusses the differences between App Registrations and Enterprise Applications, I understand the difference between these two concepts now.
Here's the situation I'm dealing with at work - I am able to create 'New registration' under App Registrations blade, however, when I go to the Enterprise Applications blade, the 'New Application' button is disabled for me. Azure AD indicates I have the 'User' role. What role/permissions should one have in order to be able to 'Add Application' in the Enterprise Applications blade?