To install the macro inside of fusion, download the .setting file.  Copy the settings file to the macro directory on your computer and restart Davinci Resolve.  After resolve is restarted, open a fusion composition.  You can either open the effects panel and click tools->macros or enter CTRL+SPACE and search for ShapeShifter.

PC: \Users\%username%\AppData\Roaming\Blackmagic Design\DaVinci Resolve\Support\Fusion\Macros

MAC: /Users/YOUR-NAME/Library/Application Support/Blackmagic Design/DaVinci Resolve/Support/Fusion/Macros