Well yes, those zpak*.pk3 do not exist anymore, due to the way 4.2 is delivered via the updater. The pk3 archives were split up to allow for faster updates.
Basically you need to extract all zUrT*.pk3 files in your q3ut4 folder. Remeber to setup a full copy of your game for mapping though.
Thechnically, you could still be using 4.1 assets, as they mainly havent changed, but if you have no setup yet there is no point in doing so.
All other steps of this guide should still be the same though.
Never the less i recommend heading over to custommapmakers.org. its all about (urt) mapping, and they also have a tutorial section, fourms and wiki over there.
click me to get to CMMs tutorial section
Also, i do agree with the above post, if you dont have done mapping with gtk or similar tools (aka mapping for quake,..) i would recommend starting in Unreal Engine.
While the current game still runs on idtech3, and thus wont be able to load your map, it will be ready for UrT HD, which is in the making and starting to look really good :)
This way you would spend your time getting into the engine that future UrT will be based one, and probably have something ready for HD release.
IF you want your map to be playable very soon though (e.g. 4.3 or even 4.2) that is a different story.
This post has been edited by Iye: 02 February 2016 - 11:20 AM