I have a new computer running Windows 8.1. I can't find a download for Digital Photo Professional that will work.
DPP 22.214.171.124 will work under Windows 8.1. DPP 126.96.36.199 will run under the 64-bit version of Windows 8.1, though it will edit only pictures taken by a FF camera.
and download the Solution Disk. That will install all the Canon software for your operating system.