I notice you’ve mentioned — this appears to reference a specific version (possibly 1.27 ) of the CineMatch plugin for DaVinci Resolve, distributed as a .zip archive.
Apply the plugin to a node in the Color page. A dialog box will appear asking for your serial number. Enter the key that came with your legitimate download.
/Library/Application Support/Blackmagic Design/DaVinci Resolve/Support/OFX/Plugins/C:\Program Files\Common Files\OFX\Plugins\