So I've started making this on ZeroRadiant now and the following error comes up when I try to export to bsp.
Failed to execute the following command: "C:/Users/User/Documents -connect 127.0.0.1:39000 Personal Documents/Urt Maps/ZeroRadiant/q3map2" -v -connect 127.0.0.1:39000 -game quake3 -fs_basepath "C:/Users/User/Documents/ -connect 127.0.0.1:39000 Personal Documents/Urt Maps/UrbanTerror/" -meat -fs_game q3ut4 "C:/Users/User/Documents/Personal Documents/Urt Maps/UrbanTerror/q3u4/maps/Quayfront.map"
Check that file exists and that you don't run out of system resources.
The file Quayfront.map exists and the PC has enough system resources.