UTCacheCleaner3 a great simple program. For ordering cache *.uxx files to individual UT files, which I have been using for years.
It only seems to me that it will not allow you to install this mutator in the game. There may be a shortage of files referring to some of the values of other data and used by the host server. I mean simple *.Int files.
*.Umod as Mr. Snowguy wrote - if you have a correctly installed game, it is not a problem with the application of the *.umod files. If you do not have a correctly installed UT, you can try to connect the *.umod file with the unrealtourment\system\Setup.exe installation program.
