JohnnyEnglish tutorial Adding Urt5 mapping entities to the Urt5 tutorial map
Introduction
If you previously made maps for UrT4 using Radiant you will be familiar with the Q3 entities, these are listed in full here if you're interested.
The Urt5 Mapping Plugin provides those entities as UE4 blueprints which can be added to your UE4 map so that Urt5 recognises it as a compatible map.