If it’s an MS OS, and you’re not making the filenames longer, just go
ren AAA* CCC*
(If they’re using 8.3 filenames, and you try to prepend longer text, the result could be not what you want. If they’re using long filenames already, it’s okay.)
I’m with Nanoda - Windows already has a rename command with wildcards. Why go with an additional utility when the capability has been part of Microsoft OS’s for 20 years?
I just select the files in Windows Explorer, F2 to rename, and enter the new name. It renames them all like Filename (1).doc, Filename (2).doc, etc. Would this work for you?
It appears to be much more capable than the native Windows rename command, and it’s definitely a lot easier to use. It gives you many options to insert file metadata into the new name, for example; the date a photo was taken is the only thing from the list that I use with any frequency. (I’ve found file renaming in Windows maddening - the wildcards don’t act the way I expect them to and I just screw everything up. I can then go back and fix it with Rename Master…)