We have fixed the custom maps problem with UK2 and we now offer only one large map file for the custom maps of each game type.
At this point there are only two maps files for download - one for CS and one for CS:Source.
The links to the files are -
http://www.cyborg2.com/files/maps/uk2-all-cs.zip - CS Maps
http://www.cyborg2.com/files/maps/uk2-all-source.zip - CS:Source Maps
The Map files are quite large at 375meg and 800meg respectively, but this is due to the nature of the newer source maps that the file is this size.