Go to https://www.qt.io/download-open-source/#section-2 and scroll down to the Qt Creator section. Follow the Qt Creator 4.2.1 for Windows link to download the Qt Creator installer.
Run the installer to begin the installation.
It is not necessary to create a Qt account to install Qt Creator. If you don't have or want a Qt account, just press the Skip button.
Qt creator should not be installed in a directory whose path contains spaces. Also, the ComfilePi SDK will look for Qt Creator in the C:\Qt directory, so it is recommended to not change it.
After installation is finished, uncheck the Launch Qt Creator and press the Finish button to finish the installation; Qt Creator can be launched after installing the ComfilePi SDK.