Those 2 answers are incorrect. You cannot install a partition in bootcamp just like that because it will say that you don't have the software or couldn't find the software, I just tested it. Luckly I had the same error as the asker and what I did was just to try to download the support within the bootcamp software and it keep saying error. So I waited and tried again, I think I tried 6 or 7 times at different times, I thought my OS had something lol
Once I saw the download was working again, I proceeded with the normal (full) process selecting the 3 of them.
To summarize, the download link is not brokes as others described, it works, just try again and again until you get it going. As we speak I'm downloading it.
Here are some useful links too:
https://support.apple.com/kb/DL1630?locale=en_US
https://support.apple.com/downloads/macoscomponents
Hope it helps.