On the newer Mac OS's the Keyfinder installation package is sometimes flagged as Untrusted and your OS will not allow it to be installed. If you encounter this, please do the following
Open the Terminal application on your Mac
Type the next command and then hit space (but don't press Enter yet): sudo installer -pkg
Next,
Drag and drop the .pkg file onto the Terminal, which will automatically
enter the path of the file. The package file can be found here:
/Applications/SongSurgeon5.app/Contents/Resources/KeyFinder.pkg
After dropping it on the Terminal App, Press Enter.
Next.....you will be asked to enter your administrator password.
Next, type it in, and the installation process should begin and complete for you.
If this does not solve your problem, please complete an incident support ticket.